[HN Gopher] More than you cared to know about PC fans
___________________________________________________________________
More than you cared to know about PC fans
Author : dankamongmen
Score : 158 points
Date : 2022-11-22 03:04 UTC (1 days ago)
(HTM) web link (nick-black.com)
(TXT) w3m dump (nick-black.com)
| rajup wrote:
| Ah reminds me of the time when I was a kid and my PC would
| randomly crash and would not start for a while. Turns out the
| processor fan was janky and would not start occasionally
| requiring a push with a pen or something to get it going. So the
| POST process in my case had an extra step: "have human check CPU
| fan"!
| themoonisachees wrote:
| Same, but my motherboard actually checked the fan was spinning
| so post literally involved me checking the fan when told
| amelius wrote:
| How does a fan get power to drive the tach output, if the only
| power it gets is a pwm signal (which might be low when it needs
| to switch)?
| exmadscientist wrote:
| It doesn't. They're almost always open collector/open drain
| signals, with the pull-up on the host (PC) side. No power
| needed, if you've got mechanical switches doing the
| commutating!
|
| (Of course those aren't so reliable over the long term, so
| transistors are usually used. But swinging a base or gate
| around is all that's needed, and that is easy to do with almost
| any available power source. Like the main power for the fan!)
| mrWiz wrote:
| Generally the fans are powered with a steady state DC source
| and the PWM is just logic signaling. If the fan is powered by a
| PWM source the tach output will not be a clean square wave (but
| could still be reconstructed, if the PWM frequency is
| sufficiently higher frequency than the fan's rotational speed).
| amelius wrote:
| Well, PC fans come in 3-wire and 4-wire forms, where the
| 3-wire type has only pwm,tach and GND connections (no DC
| power).
| robotguy wrote:
| 3-wire is: TACH, DC, GND
|
| 4-wire is: PWM, TACH, DC, GND
|
| https://noctua.at/en/what-pin-configuration-do-noctua-
| produc...
| amelius wrote:
| In practice pwm is used instead of DC.
| wtallis wrote:
| I can't remember the last time I encountered a
| motherboard that didn't offer you the choice between DC
| voltage and PWM for fan speed control. Both are still
| mainstream options; CPU heatsink fans are almost always
| 4-pin PWM fans but case fans are very commonly 3-pin DC
| fans. AIO Water cooling kits also commonly use 3-pin
| fans, especially when integrating their own fan
| controller or multiplexer so that they only need to
| occupy one or two fan headers on the motherboard.
|
| (Edit: if you mean that in practice, the motherboard
| approximates DC voltage control using a PWM-based method,
| that may be true, but it's beside the point; a 3-pin fan
| is missing the control circuitry that a 4-pin PWM fan
| uses, and the 3-pin fan's behaviors like turn-on point
| will be specified in terms of DC voltage not PWM duty
| cycle, and you can't drive a 3-pin fan with the PWM
| signal intended for a 4-pin fan because the voltage and
| current supplied are both far too low.)
| azalemeth wrote:
| Honestly this isn't more than I cared to know about PC fans. I've
| worked extensively with industrial appliances and fans are bloody
| important and underlooked: fan failure is often the step that
| precedes component failure. The one part of the spec I wasn't
| aware of was just how insanely high the maximum current draw is;
| I'm glad that we've made more efficient, longer-lasting,
| effectively silent air-movers that can fit easily within that
| power budget.
| rietta wrote:
| Adding fans to consumer devices that don't have them but
| should, such as a cable modem, certainly improves its
| reliability in my experience!
| Eisenstein wrote:
| The problem with that is when the fan would block the natural
| venting if it stops working. These devices are engineered to
| have the heat move the air through and out of the device, and
| though a fan will usually do a better job of that, it will
| ultimately fail. When it does, if the fan body is in the way
| then the intended convection is blocked and the entire unit
| shuts down or is damaged.
| Retric wrote:
| Cable modems are often placed in poorly ventilated spaces
| that overheat. So you can get the best of both worlds by
| including generally unneeded fans which enable the device
| to function in sub optimal conditions, but can also extend
| lifespan in better ventilated spaces.
|
| The alternative of passive cooling in such spaces is
| unreasonably expense because only a subset of devices are
| subjected to such conditions.
| rietta wrote:
| I have thought about adding a bathroom style vent fan to
| the closet that houses the network gear for the house.
| Exhaust near the top and have a cool air intake near the
| floor.
| js2 wrote:
| AC Infinity make fans specifically for this purpose:
|
| https://acinfinity.com/closet-room-fan-systems/
|
| Bathroom fans work too if you're able to vent through the
| ceiling. I can recommend the Panasonic whisper fans
| (available under a variety of models with "whisper" in
| the name). I'm using one to exhaust the warm air from my
| home theater emitted by the projector. I think it's this
| one:
|
| https://na.panasonic.com/us/home-and-building-
| solutions/vent...
| post_break wrote:
| Slow big fans on my home receiver kept it going much longer
| than it probably would have lasted passively cooled.
| aidenn0 wrote:
| Can you recommend a fan setup for that?
| post_break wrote:
| AC Infinity usb fan on amazon. Silent, but moves enough
| air, and you can bump up the speed.
| deathanatos wrote:
| Also, one thing I've always wondered: why do people _want_ to use
| hwmon to set fan RPMs? (Or really, why do this from userspace at
| all?) It seems inherently dangerous to me, as you 're asking a
| process who might not receive CPU time for whatever reasons from
| the very much not realtime OS to control a fan; if the current
| RPM is too low, and the system starts generating heat, but the
| fan controlling process doesn't get CPU time ... then what
| happens?
|
| It seems to me you want fans controlled with something dedicated
| to it.
|
| The other thing I don't get is all the plethora of options my
| motherboard gives me to set fans only to fixed RPMs. Am I crazy
| in that I want the fan to be controlled by heat? (More heat =>
| more RPMs. Keep the system cool, but if there isn't much thermal
| load, spin the fans down and reduce the noise?)
|
| But by fixing an RPM, it seems the only valid input is "100%";
| anything else could be too low under stressful conditions.
|
| I could also have a cheap motherboard. (I definitely won't be
| purchasing from this manufacturer again, and the motherboard does
| have other severe quality issues...)
| toast0 wrote:
| > why do people want to use hwmon to set fan RPMs? (Or really,
| why do this from userspace at all?)
|
| Some people want to have a mode switch; normal use should be
| silent/quiet, but when you know you're going to do something
| big (game, big compile, etc), fix the fans at full so the noise
| is consistent and cooling is best. (the cooler the chip, the
| more the boost)
|
| Some people have no good options from the system firmware, and
| getting _something_ configurable is better. I've run on systems
| where I couldn't tell the system to actually run the fan, so
| things would get hot and throttle. Userspace configurability is
| better than nothing. This tends to be a bigger issue on things
| that are sold as a whole computer, like laptops, and small
| formfactor things (which are often pretty much laptops without
| a battery and built in user interface devices) but also some
| name brand desktops.
|
| My recent motherboards all seem to have a pretty nice fan
| configuration tool. Presets for quiet/performance/full speed,
| and a simple graph based UI to set % by temperature. Most of
| the fan headers can be set to follow the cpu temperature or the
| system temperature. When you buy the nice Noctua fans, they
| also ship 'low noise adapters' that I assume drop the voltage
| and limit the maximum RPMs and limit noise. Depending on your
| overall cooling design, that can be reasonable or asking for
| trouble.
| deathanatos wrote:
| > _Some people want to have a mode switch; normal use should
| be silent /quiet, but when you know you're going to do
| something big (game, big compile, etc), fix the fans at full
| so the noise is consistent and cooling is best. (the cooler
| the chip, the more the boost)_
|
| Yeah, I don't doubt someone is like that ... I'd just rather
| it be automatic.
|
| > _My recent motherboards all seem to have a pretty nice fan
| configuration tool._
|
| Mine has a "flashy" tool, I would say. Certainly looks
| pretty, but again, it's all constant RPM options.
|
| As I lament in the other thread, this is something that would
| differentiate boards at time of purchase, but no mobo
| manufacturers marketing dept. seems to have it's shit
| together enough to get such a differentiation across to the
| consumer. Instead the focus seems to be completely on the
| aesthetics of how the board looks.
|
| And again, I've chalked this up to having chosen poorly. But
| there-in is the problem: assuming I chose poorly, assuming
| some mobos _do_ support sane defaults /fetures ... how do I
| end up finding and purchasing one of those? Any knowledge I
| acquire during a purchase is useless the next time around,
| given the constant product churn HW manufacturers
| nonsensically do.
| toast0 wrote:
| The two boards I've gotten recently advertise the features:
|
| https://www.gigabyte.com/Motherboard/A520I-AC-rev-1 look
| for "Smart Fan 5", there's a tab you can click and see what
| the customization UI looks like (it's in the firmware
| settings usable with keyboard or mouse). ITX does mean this
| isn't a 'value' board, but when I got it the premium above
| mATX wasn't that much (and probably mostly went to the
| wireless I don't really need and barely ever use)
|
| My other board is a bit more upmarket
| https://www.asrock.com/mb/AMD/B550M%20Pro4 it doesn't show
| anything on the marketting page, but in specifications it
| mentions "Smart Fan Speed Control" and the UI to configure
| it is pretty similar.
|
| You get to set about 5 temp -> fan % settings and I can
| keep things cool without being noisy until I've got
| sustained load and then it's noisy and warm anyway. The ITX
| systems can only do so much with a cooler + heatsink height
| of 36mm (at 37mm the fan housing touches the mesh side
| panel), and the b550 currently has an anemic Wraith
| Stealth. Even with 65w target chips, that's not enough to
| keep them below 90C at high load.
|
| I think my older boards have basic quiet/loud/full speed
| settings but not detailed ramp settings; but it's been a
| while and they're either hidden in the basement/garage or
| not used often so I didn't care about noise. :D
| MaulingMonkey wrote:
| > It seems inherently dangerous to me
|
| In the old days, it kinda was - at least to your hardware.
|
| Then people realized that blowing up components because a fan
| failed, or became unplugged, or a filter clogged with dust,
| _maybe_ wasn 't a great user experience and/or caused more in-
| warranty returns that required replacing hardware
| ($$expensive$$!), and implemented thermal throttling and
| thermal cutoffs. Nearly _two decades_ ago at this point, I
| helped a friend diagnose his computer randomly turning off. It
| turned out to be a CPU fan unplugged itself, causing
| overheating to trigger a thermal cutoff. No other apparent harm
| done.
|
| Fans aren't the only means of limiting heat: slowing stuff down
| and turning stuff off also works. And it turns out users
| sometimes would rather stuff run slow than run loud, and maybe
| your crappy motherboard vendor shouldn't be writing a ton of
| code running in kernel space - with all the potential stability
| and security issues that might entail - for whatever network-
| connected bloatware syncs your RGB lighting and fan settings to
| the cloud. And they _will_ do exactly that, if that 's what's
| required to give their customers what they want.
|
| Just exposing fan RPMs to userspace might be far less
| dangerous.
| LorenPechtel wrote:
| Yup, I got random thermal shutoffs. The pump in the water
| cooling loop had failed.
| deathanatos wrote:
| > _and maybe your crappy motherboard vendor shouldn 't be
| writing a ton of code running in kernel space - with all the
| potential stability and security issues that might entail_
|
| This wasn't the suggestion I was making. I was suggesting
| that the motherboard, _itself_ , should be controlling the
| fan RPMs (or should at least provide such a mode). I don't
| feel like taking a temperature input, and mapping that to an
| RPM output should take much circuitry at all, but it that
| (somehow) required a full-blown CPU, I was thinking a (very
| small) auxiliary chip, dedicated to the task.
|
| But yes, if you're going to do it on the main CPU, then in
| userspace. But now you incur all the problems I mentioned in
| the original comment, some of which can exhibit death
| spirals: CPU has to throttle due to heat, meaning less CPU
| time, meaning it will take longer to get to the code
| responsible for alleviating the problem of heat by notching
| the RPM up!
|
| In the worse case, you hit the CPU's critical trip point
| before the problem can be brought under control.
| wtallis wrote:
| On typical desktop motherboards, the Super IO chip handles
| all the temperature monitoring and fan control. Those chips
| usually have a few modes to configure some very simple
| control system for mapping temperature inputs to fan speed
| outputs (never anything as advanced as a PID controller).
|
| The main problem is that the Super IO only has access to
| the temperature sensors on the motherboard itself, and on
| the CPU (these days, through PECI). There's no standard way
| for the Super IO to do out of band monitoring of
| temperatures on your GPU or storage drives, so if you want
| those to affect fan speeds you need to implement it in
| software.
|
| Servers typically have BMCs controlling fans, and even
| Apple's x86 machines have their SMC; in both cases you
| typically see a more thorough monitoring of component
| temperatures, configured out of the box with a proper
| awareness of which fans are blowing across which
| components. But that stuff doesn't trickle down to the
| build your own desktop market.
| deathanatos wrote:
| Hmm. I guess I have no idea how this chip interfaces with
| the kernel then? The only knobs that seem to be
| documented to exist ever are direct RPM controls for
| manual control.
|
| I know it's _possible_ (despite the insistence to the
| contrary on the other thread), as basically every laptop
| does it. Only do desktops seem to struggle with this
| concept.
| wtallis wrote:
| How fan control is configured depends on the SuperIO
| chip, so it's different for eg. Fintek SuperIOs than for
| Winbond/Nuvoton SuperIOs.
|
| On Linux, a supported SuperIO will be exposed as a
| directory under /sys/class/hwmon. On one of my systems,
| the SuperIO is a Nuvoton NCT6791, so the relevant driver
| documentation is
| https://www.kernel.org/doc/Documentation/hwmon/nct6775
|
| Relevant sysfs files to note are pwm[1-7]_mode to toggle
| between DC voltage and PWM control, and pwm[1-7]_enable
| to switch between full speed, pure software speed
| control, and several Nuvoton-specific automatic speed
| control modes.
| MaulingMonkey wrote:
| > I was thinking a (very small) auxiliary chip, dedicated
| to the task.
|
| Extra cost (both in design and manufacture), new potential
| point of failure (both for manufacture and in the field),
| when the CPU failing was already a single point of failure
| for the machine. It's not that a full-blown CPU is
| required, it's that you already have a full-blown CPU that
| can do the job, simplifying the design. Well, you might see
| dedicated fan control hardware for server motherboards and
| other more industrial focused applications, but they often
| need to coordinate pumps/fans for an entire building -
| reliability in this context is more about redundancy, and
| alerting maintainence to the need for repairs, or perhaps
| switching to a new primary datacenter if the failure is big
| enough - not in attempting the impossible of ensuring 100%
| reliability for any individual component.
|
| > CPU death spirals
|
| Have you actually seen one of these that noticably bogs
| down the fan-driving firmware/drivers and causing issues? I
| haven't. I've had fan failures. I've had plenty of hardware
| controlled fans go full apeshit 100% power to the point of
| being not merely a nuisance, but a problem (audio,
| vibration, wear+tear, ...). I've heard of building cooling
| failures. But I don't think I've seen so much as a blog
| post about the CPU getting so starved that it can't spin up
| the CPU fans.
|
| And I've had fans not working hard enough - but I'd rather
| flip a setting in software than open up a case and go
| hunting for the right jumper, typically. Less disruptive -
| and the machine is typically usable enough I can still
| download/install missing software, and google appropriate
| documentation, which is frequently a lot more difficult to
| do with the case open.
|
| ---
|
| I guess my main point here is that reliable hardware must
| already assume the potential for cooling failures, and that
| extra hardware or engineering for a minor improvement to a
| "purely theoretical" failure mode doesn't sound like it'd
| pay for itself.
|
| 100% have hardware temperature throttles and cutoffs
| though. Those cut in for a lot of very real failure modes,
| that I've only heard of actually happening, but personally
| experienced. Those _will_ pay for themselves.
| deathanatos wrote:
| > _Extra cost (both in design and manufacture), new
| potential point of failure (both for manufacture and in
| the field)_
|
| "But the BOM" is a tired trope in any discussion about
| "why can't it do X?". My money would be where my mouth
| is. But HW manufacturers routinely make design decisions
| that are simple negatives.
|
| Motherboard manufacturers, in particular. Mobo marketing
| is focused on colors and flashy effects instead of on
| quality of production and actual function, beyond a bare
| minimum of tech specification. AFAICT the products are
| indistinguishable as no attempt is made to stand out.
|
| > _when the CPU failing was already a single point of
| failure for the machine_
|
| ... and so is the RAM, the disk, the GPU, the
| northbridge, the southbridge, the eastbridge...
|
| That's not a valid rationale for "let's a adopt a
| fundamentally flawed design".
|
| > _Have you actually seen one of these that noticably
| bogs down the fan-driving firmware /drivers and causing
| issues?_
|
| "Fan-driving firmware" is essentially the suggestion.
| It's what I haven't got.
|
| > _I 've had fan failures. I've had plenty of hardware
| controlled fans go full apeshit 100% power to the point
| of being not merely a nuisance, but a problem (audio,
| vibration, wear+tear, ...)._
|
| No; in my current rigs 10 year lifespan, the fans have
| been run continuously at 100%, and no _fan_ failures.
|
| The noise, of course, is a nuisance. That's why I'm
| looking for something that can control the fans in
| response to temperature, such that the fans can be driven
| at a temperature-appropriate RPM.
|
| But without doing that in userspace, where the controller
| might just "die" or effectively die, for any number of
| reasons, outlined earlier.
|
| > _But I don 't think I've seen so much as a blog post
| about the CPU getting so starved that it can't spin up
| the CPU fans._
|
| I couldn't find any posts reasoning about anything.
| Either it's not a problem, or just nobody is thinking.
|
| > _and that extra hardware or engineering for a minor
| improvement to a "purely theoretical" failure mode
| doesn't sound like it'd pay for itself._
|
| Yeah, I was just trying to learn before attempting,
| literally, "IDK, try it and see if you trip the critical
| temp cutoff."
|
| Yeah, no doubt the various hardware safeties will save
| you (although it might put some undue stress on stuff to
| be at >100...) but it might also leave you with a rather
| hard-to-debug situation if you start experiencing stalls
| or shutdowns.
|
| ... and it's only in desktops that this problem seems to
| exist. On every laptop I've owned, fan control is in
| response to temp. (And not handled in userspace, although
| I presume I could download any of the various fan control
| programs and have it be that way, but the point is that
| the HW is, out of the box, doing the sane thing.)
| whalesalad wrote:
| What a coincidence, 4x of the 120mm Noctua Redux fans just
| arrived this morning and are sitting on my living room table
| waiting to go into my rig. I love in-depth analysis of stuff like
| this.
|
| How do y'all like to manage (chassis) fan speeds? I have been out
| of the PC world for so long that I forget all pieces of hardware
| need to be managed.
| ChoGGi wrote:
| I use a Corsair commander with a copy of system information
| viewer
| whalesalad wrote:
| Dig the fact that this thing comes with little temperature
| probes - my current case is probably a little too small for
| the setup I have right now and I am debugging the temperature
| zones / airflow. It's a Fractal Define C, i7-12700K, Radeon
| RX 6750XT OC. Initially my CPU cooler fans (2x) were pointed
| in opposite directions, lol. Would love a thermal camera, but
| these probes would probably be just as helpful.
| MivLives wrote:
| 4 way fan splitter to just let the mobo control it all. I run
| mini itx so not a lot of fan headers.
| gregmac wrote:
| FWIW I used to use software (Speedfan, and later something else
| I don't remember), but after upgrading to Noctua fans, I found
| whatever is built-in to the motherboard works just fine and
| gave up on the complication of software. I'm on my second
| system like this, and I've found they've both been a good
| temperature and nearly silent most of the time. Even maxed out,
| it still seems to be quieter and cooler than it would be with
| most (cheap) fans.
| whalesalad wrote:
| nice, that was what I was hoping to achieve
| tristor wrote:
| This was a great read, I have always had a love of PC fans, and
| the technology behind them. It'd quite a complicated engineering
| challenge to produce a high static pressure, high rate of
| airflow, and minimize noise while maintaining high reliability.
| I'm one of those folks that has no problem dropping significant
| money on fans every time I do a PC build, and so far I have very
| very rarely ever had a fan fail on me, even after decades of
| running at high duty cycles. The thing I always marvel at is how
| high the draw is for some of these fans. At one point I even
| retrofitted a system with an external radiator for water cooling
| that used 120V 120mm Panaflos and was separately powered from the
| computer.
|
| I wish folks took cooling more seriously. There are so many
| devices that benefit from active cooling but rarely get it, or
| even being strategic around placement, positioning, and mounting
| to make convective cooling more effective. Thermal limiting is
| such a common occurrence on modern electronics if you don't give
| due consideration to cooling, as we've moved towards more
| passively cooled devices, including PCs (laptop especially).
| nodoodles wrote:
| Great to know, though more of a Mac fan myself... (sorry)
| magicalhippo wrote:
| What I want to know is how a ballbearing-less fan suddenly
| decides to go brrrrrrr.
|
| So far I've been lazy and just replacing them, but I'd be nice to
| know as they seem fine when I spin them manually.
| hoseja wrote:
| Are you sure it's not a resonance elsewhere?
| magicalhippo wrote:
| Yes, if I run the fan stand-alone it will start to brrrr
| after a short while.
| LooseMarmoset wrote:
| Those kinds of fans typically use a bronze bushing rather than
| a bearing. These bushings are long-lived, but eventually wear.
| When the bearing hole enlarges as part of the wear process, the
| fan rotor shaft now has additional room for lateral movement in
| the bearing and can oscillate in the the bearing rapidly,
| causing the "brrrrr" noise you hear.
|
| You can often extend the life of such bearings by adding a drop
| of light machine oil to the bearing (usually you have to pull
| off a sticker on the back of the fan to access the bearing).
| HPsquared wrote:
| I'd imagine the fluid bearing gets a bit worn over time such
| that it's a bit "looser", i.e. doesn't hold the fan rotor as
| firmly in a straight/central position.
|
| Not enough movement to sense by hand, and no roughness, but
| enough looseness / free-play to allow a kind of resonant
| vibration or "wobble" when the fan is spinning faster.
|
| Edit: or maybe it's just very slightly worn, has debris in the
| bearing or something, such that it's out-of-round. I think it's
| the former though (resonance) as that kind of noise can be
| intermittent.
| bayindirh wrote:
| Nick Black's personal wiki is a treasure trove. The style is a
| little terse, but it's a non-issue for me.
| ilyt wrote:
| I'm surprised it doesn't mention hysteresis some fans have at low
| speed.
|
| Cheap fans often don't have actual proper speed controller on
| them which means they might start spinning at say 30% PWM but
| only stop spinning at 15% PWM. That was probably the thing that
| surprised me most when I upgraded to nice Noctua, at certain PWM
| it just started, always, and below that it stopped, always.
| paxswill wrote:
| Those fans that start at 30% and then allow you to go lower are
| explicitly allowed by the spec from Intel (linked in the
| article, sec 3.2 and 3.4).
| Scene_Cast2 wrote:
| One interesting thing to note is the P/Q fan curve. It plots how
| much air a fan, at a specific PWM frequency, moves against a
| variable restriction (measured in pressure drop). Here's a sample
| - https://noctua.at/en/nf-a12x25-performance-comparison-to-nf-...
|
| Hypothetically, knowing the heatsink airflow curve, one can find
| the amount of air a fan will move across.
|
| There are PQ curves (either reported or measured) for a bunch of
| fans and some radiators out there.
| rietta wrote:
| Nick has been a prolific writer as long as I have known him. This
| is some great, esoteric stuff, about fans. I have used case fans
| in unusual applications not involving a computer but never went
| deeper than provide sufficient power that it spins full speed.
| For my own builds, I usually just plugged the fan in without a
| second thought.
| Markoff wrote:
| I haven't assembled PC in long time, by now I'd expect you can
| build passively cooled PC if you use PC just for some regular
| office job and surfing without gaming and resource heavy apps or
| we are still not there? Back in the days undervolting was for me
| for interesting than overclocking to make PC as quiet as
| possible.
| kadoban wrote:
| Some passively cooled PCs exist, but they're niche and
| expensive.
|
| It's a lot easier to make one that's quiet, but not silent. Big
| fans that spin slow and not going crazy with bleeding-edge
| hardware do wonders. Yeah, if you really want, you can try to
| underclock/undervolt some things here and there.
| wtallis wrote:
| I think it's useful to draw a distinction between a _silent_
| computer and one that is merely _inaudible_. For a typical
| PC, all you really want is for it to not noticeably raise the
| noise floor of the office it occupies. Going down the route
| of truly silent PCs forces severe compromises, and in almost
| every use case it would be better to have fans, properly
| configured to always spin, with a minimum speed low enough to
| be inaudible.
| scns wrote:
| It is absolutely possible, even with a high performance GPU!
| [0] A video review by LTT [1]
|
| [0] https://www.monsterlabo.com/
|
| [1] https://www.youtube.com/watch?v=_jYB-RpkmUc
| owenversteeg wrote:
| Does anyone know if there are high-heat-resistant PC fans (and at
| what temperatures normal PC fans will melt)? The only fans I can
| find that claim to be heat-resistant are the Noctua Industrial
| PPC series which, aside from not being cheap at $33/piece are
| "only" heat-resistant up to 140C and the airflow isn't crazy high
| - subjectively the ones I've got feel like they move
| substantially less air than a standard diesel heater blower fan.
|
| Ideally I'd be interested in something that's >180C resistant but
| if there are any other options around say 140C max then I'd also
| be interested.
| jenscow wrote:
| I prefer fans that are _not_ heat-resistant. That way, it has
| more motivation to do its job properly.
| fnordpiglet wrote:
| The melting will stop when cooling improves.
| lazide wrote:
| Why?
| ChoGGi wrote:
| All he has is a hammer?
| lazide wrote:
| I'm just amazed at how specific of not-nail he seems to
| trying to drive with it!
|
| Those are high temperatures for anything electric.
| michaelt wrote:
| Unfortunately many plastics, and the most common types of
| solder, start softening before you get to 180C. You can get
| smoke extraction fans and chimney flue fans that will tolerate
| higher temperatures, but they're generally an all-metal affair
| costing more than $33.
|
| Assuming the 180C is at your system's ventilation output, could
| you move your fan to the air inlet so it only has do deal with
| ambient temperature air? That's what's done for blacksmith's
| forges etc
| owenversteeg wrote:
| Yes, chimney flue fans were next on my list but surprisingly
| enough the airflow for most of the shelf models is quite low.
| Unsurprisingly with all metal parts and less competition in
| the sector the performance is also far worse in terms of
| watts/CFM. Pushing ambient air sadly doesn't work for my
| application. That said those would have all been great
| suggestions though so thanks!
| tinco wrote:
| If $33 is not cheap then maybe not. But I buy my delta fans at
| mouser or digikey, and they have a wider range of specs than
| typical consumer websites. They come without connectors though
| so there's some crimping/soldering required.
|
| For our little rendering cluster I bought a bunch of 12.000 rpm
| fans to cool the rack mounted threadrippers. Worked fine, no
| watercooling in the rack needed and 4ghz on all cores under
| load.
| somat wrote:
| For some reason I got all opinionated about fans and settled
| on delta as my preferred brand. I think because delta
| actually had data sheets. The cool thing is that digikey has
| the exact fans I want, the downside is that the fans digikey
| sells have no plugs.
|
| I tried once to terminate it myself but I was too cheap to
| buy the correct tools, so that did not go well. and am now a
| bit bummed about the whole thing, I found a vendor I can
| trust to sell me real delta fans.. and they have no plugs.
| _sigh_ will probably stick with nocturna as a good second
| best.
| mrWiz wrote:
| The DC brushless fans listed on Digi-Key max out at 100C;
| anything rated to 140C or high would be extremely specialized
| and costly.
| userbinator wrote:
| If $33 is "not cheap" then you're not going to find anything
| lower. Perhaps an oven fan, but that's a different form-factor.
| The problem is that fans with integrated motors are limited by
| the temperature of the motor, and motors designed for high
| temperatures are also not cheap since special materials need to
| be used.
|
| ...and what's the reason behind needing such a fan?
| owenversteeg wrote:
| $33 is cheap enough for a handful for myself of course but as
| you may have guessed I'm thinking of releasing a product that
| would need them. Not a serious thing, more so a handful of
| bulk bought parts sold together to scratch a long standing
| itch in a very very specific field. Sadly $33/ea would really
| eat into the BOM, even on an expensive mass produced item
| like an iPhone that would be one of the most expensive parts.
| axiolite wrote:
| > "there is no readily-available 24V source from an ATX power
| supply,"
|
| This is false. ATX provides both +12V and -12V: *
| https://pinoutguide.com/Power/atxpower_pinout.shtml
|
| Hooking them together would provide 24VDC. On a 350W PSU, I see
| -12V rated to supply 0.3A, which would allow for 24V fans drawing
| up to 7.2W of power, if desirable.
|
| I don't see any reason to prefer 24V fans, however. The current
| losses over such short ranges are minimal, and I would think the
| larger economies of scale of 12V devices will keep 12V fans less
| expensive.
| exmadscientist wrote:
| Do not use 24V fans for anything, if you have any control over
| it.
|
| 24V fans in general are poorly stocked. 24V 4-wire PWM fans
| are, these days, more or less special order items. There are
| thousands of 12V 4-wire PWM fans in stock at Mouser and Digi-
| Key. There are less than a dozen 24V 4W fans in stock, and most
| of those are sizes you probably don't want.
|
| I'm a consulting EE these days. One of the jobs I get to do is
| clean up designs that aren't working. We always flag these fans
| when we see them... then nothing gets done because they're
| "available enough"... then when build time comes we can't
| source the fans because the "stock item" is completely out of
| stock and all possible substitutes are out of stock. But 12V
| versions are available.
|
| So, yeah, stick to 12V fans _whenever possible_ (or 5V for the
| little guys). Also genuinely never use AC fans, but that 's a
| different story.
| balfirevic wrote:
| > 24V fans in general are poorly stocked.
|
| I'm guessing the same holds for 48V fans?
| gnu8 wrote:
| This led me to wonder why we still need the -12V supply - I
| know the -5V supply was removed a while ago because it was only
| needed for ISA slots. According to Wikipedia, -12V is for
| RS-232 ports and PCI slots, both of which are hardly seen on
| any current motherboards. It should be safe to use it for fans,
| but 7.2 watts is not very much power. Looking on Mouser, I see
| 24VDC fans that consume 1 watt or 18 watts depending on speed,
| so one could easily overload the -12V bus if they are trying to
| get a lot of CFM. I don't see a compelling reason to use 24V
| fans in a PC.
| iknowstuff wrote:
| I _think_ the ATX12VO standard might be getting rid of -12V.
| All it does is 12V.
| 0cf8612b2e1e wrote:
| Any chance they are going to add something higher? 19v
| would align with laptops and make power hungry GPUs
| slightly more manageable.
| chipsa wrote:
| I'd suspect they'd go up to like 48V. It's the max
| voltage for USB-PD 3.1, which corresponds with being the
| effective highest voltage you can have before you're no
| longer "low voltage". This is also why PoE is
| approximately the same voltage.
| toast0 wrote:
| From what I've read, ATX12VO really is 12V only; peripheral
| power connectors (sata/molex) will be connected to the
| motherboard, where the 5v and 3.3v (if needed) will be
| generated. 3.3V on sata power plugs was never reliably
| available and was rarely if ever used, and one of the pins
| was redfined to be a disable pin, so it's usually best for
| everyone if 3.3V isn't provided at all.
|
| -12V for RS-232 is easily generated from +5V or similar
| sources; max232 chips have been available since the 80s
| deathanatos wrote:
| The pinout is wrong, is it not? As it is drawn, if you mate the
| two connectors, the wires won't match up. (You'll need to
| mentally rotate it: the hook on the back of the male connector
| slots into the rails on the front of the female connector to make
| them impossible to separate without destroying a nail.)
|
| I think the female side is right, it's the male connector that's
| reversed.
| pwg wrote:
| > The pinout is wrong, is it not?
|
| Not if both connectors are drawn looking top-down.
|
| Note the ribbing and clip on the female connector, the bottom
| of the female connector is at the bottom of the drawing. You'd
| mate these by lifting the female straight up, rotating about 90
| degrees along the vertical axis, and pushing down onto the male
| connector. And when mated that way, the labeled pin-outs line
| up perfectly.
| deathanatos wrote:
| Oh, you're right; it's drawn such that the business end's
| holes for the pins are hidden on the bottom; the wires should
| be coming out the top, but they're not rendered. (So, the
| pinout is right.)
|
| (Edit: in my defense, the CAD model's square holes on that
| end are pin holes, not wire holes, which would almost
| certainly be wider, not square, and take up more of the space
| available on that side, and do on the connector I have. Hard
| to find a photo on Google, as nobody photographs the non-
| business-end...)
| rkagerer wrote:
| This is great. I determined some time back the most important
| thing I need to know is "buy Noctua". They're expensive but have
| consistently outlived all other PC fans I've ever tried.
| egberts1 wrote:
| So looking forward to the incomplete "Form Factor" section!!!
| antifa wrote:
| I wish noctua would sell aftermarket replacement CPU fans for
| laptops. I thought there was something wrong with the loudness of
| my Dell laptop's fan (with low confidence), but I couldn't gauge
| that any replacement product wound actually be quieter or cared
| about noise levels.
| nicolaslem wrote:
| Most laptop parts are specifically designed for a particular
| laptop model. This is very different from the highly
| standardized desktop parts. Noctua would be sure to lose money
| selling laptop fans.
| [deleted]
| fiat_fandango wrote:
| Just when we thought Linus Tech Tips had exhausted every normie,
| low effort way to "investigate" which fan is best to cool a
| consumer CPU and GPU for gaming...
| wallaBBB wrote:
| Depth of fan analysis in PSU reviews you could find on jonnyguru
| beats this by a mile. Too bad jonnyguru site is no more.
| zajio1am wrote:
| One sad thing with fans in PC is how bad is fan controller /
| SuperIO driver support in Linux. AFAIK, there is no autodetection
| for SuperIO chips (like there is for PCI or USB devices) and for
| many chips there are no drivers anyways.
|
| Seems like using USB connected microcontroller with open-source
| firmware instead of embedded SuperIO seems like easiest way to
| have reliable fan control in PC.
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