[HN Gopher] Ryzen Z1's Tiny iGPU
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Ryzen Z1's Tiny iGPU
Author : rbanffy
Score : 100 points
Date : 2024-02-26 18:11 UTC (4 hours ago)
(HTM) web link (chipsandcheese.com)
(TXT) w3m dump (chipsandcheese.com)
| SunlitCat wrote:
| I really wonder why AMD is so reluctant to release desktop cpus
| with a powerful iGPU.
|
| Yeah, I know the 8x00G exists, but it's kinda too little too
| late.
| rbanffy wrote:
| Could be that they are selling all the capacity they could
| hire. In that case, they'll aim to produce just the products
| with the highest margins (meaning the more specialized ones).
| wmf wrote:
| Any better iGPU would be limited by memory bandwidth. More
| bandwidth would require a different socket and probably more
| expensive motherboard.
| SunlitCat wrote:
| Mhm, but it kinda hurts to see, that AMD is able to push out
| APUs powering the likes of a Playstation 5 and everything on
| a single chip, while on desktop you need to buy the cpu and a
| chunky gpu seperately.
| wmf wrote:
| The consoles are not socketed or upgradeable. That's the
| difference.
| bryanlarsen wrote:
| AM5 only has a 128 bit wide memory bus. (2 64 bit
| channels). So we're not going to get a usably beefier GPU
| until AM6.
|
| However, on laptops which aren't constrained by backwards
| compatibility, Strix Point Halo appears to have both a
| beefy GPU and a 256 bit memory bus.
| PaulKeeble wrote:
| The G chips are also pretty seriously crippled by the cache
| reduction from 32MB to 16MB. It hurts their compute performance
| so much they behave similar to equivalent chips from a few
| generations before as well. I suspect its done to hit a power
| target but its an unfortunate trade off making these chips a
| bit of a let down.
| jwells89 wrote:
| I've wondered this too. I would imagine that there's a
| significant market for PCs with iGPUs roughly on par with those
| of consoles... that's enough horsepower to play all esports
| titles extremely well as well as most other types of games on
| medium settings, which is more than good enough for a lot of
| people.
|
| To work around memory issues, these CPUs would need some
| onboard memory which would increase costs a bit, but the
| tradeoff is that it'd make for simpler, cheaper low-end
| motherboards. One can imagine a mini-ITX board with nothing but
| a CPU socket and a couple of M.2 slots that'd cost
| significantly less than current entry-level ITX boards. A full
| system upgrade could be performed by simply swapping out the
| CPU which would be great for non-enthusiasts; without a power
| hungry discrete GPU, power requirements are unlikely to
| increase meaningfully (and in fact are likely to _decrease_
| with upgrades), so upgrading wouldn't necessitate a PSU change.
| These hypothetical boxes could easily stay relevant for a
| decade or more.
|
| Higher end SKUs of motherboards for this type of CPU could have
| the usual RAM slots (acting as a second tier of slower RAM in
| place of swap), PCI slots, etc.
| Atotalnoob wrote:
| On die memory increases costs significantly. It would be
| premium only to put any large on die memory sets
| cduzz wrote:
| Even for chiplets?
|
| I'd expect that you could probably get okay yields at okay
| costs if you are running a process that's a rev or two
| behind and making smaller chiplets that are then wired
| together after testing -- like the pentium pro's cache but
| for main memory to get 2 / 4 / 8gb ram all on "chip"
|
| It'd probably cost more than a normal CPU, but the trade
| off is much more speed and the actual computer /
| motherboard at that point would just be a couple USB
| devices. You (the CPU maker) would grab a lot more of the
| per-unit profit.
|
| Ah -- that's why they don't do it; no vendor would want
| their milkshake drunk...
| eropple wrote:
| AMD does seem to be trying new stuff with Strix Point
| Halo, but in-package RAM seems like it'd add new physical
| challenges that probably need a defined market before
| they swing for the fences?
|
| Because it's not just the memory chip, also the
| interposer it's stacked on top of, which now needs to be
| bigger, which means you need to find more room in the PCB
| (today) or a bigger silicon interposer (likely in the
| near future) which reduces yields, and so on and so
| forth. If you wanted to have more than the very limited
| SoC RAM, you'd also then be looking at having multiple
| DRAM controllers, which also adds to surface area, and so
| on and so forth.
| bryanlarsen wrote:
| An APU with a decent amount of fast on-package memory is
| going to be expensive. $1000 maybe? It'd be odd to pair a
| $1000 CPU with a $100 mobo. Maybe it's a good idea, but the
| market would find it confusing.
| wtallis wrote:
| "Some onboard memory" for a socketed CPU is impractical.
| They're not going to make a die with a wide DRAM controller
| for on-package memory and then a second narrower DRAM
| controller for memory slots, especially if the latter was
| only going to be used for high"end systems. It'll be soldered
| CPU and DRAM or the usual sockets/slots; I don't see how a
| mixed approach would make economic sense.
| bryanlarsen wrote:
| On-package memory is coming to x86 laptop CPU's, it's a
| question of when rather than if, IMO. Apple MacBooks are
| killing x86 laptops, and a large part of the reason is the
| on-package memory. I'm sure Dell et al are screaming at
| Intel and AMD asking for competitive chips.
|
| You're right that they likely won't make 2 different dies.
| Desktop AM5 chips will just get a package with some of the
| memory controller pins unconnected. The big question is
| whether they'll also package the full width laptop chip
| with on-package memory in a package for desktop that's
| incompatible with AM5.
|
| If they don't, somebody is going to solder that monster
| laptop chip into an ITX motherboard. People will grumble
| about a motherboard that can't upgrade either the CPU or
| the memory, but if the performance is there they'll still
| buy it.
| sapiogram wrote:
| There just isn't enough memory bandwidth. Afaik dual-channel
| DDR5 still can't hit 100GB/s? Meanwhile the $270 RX 7600 has
| 288GB/s on-board memory.
| bryanlarsen wrote:
| jwells89 says "onboard memory", by which I assume they mean
| on-package memory like the Apple Mx. The M2 Ultra has 800
| GB/s of memory bandwidth...
| adgjlsfhk1 wrote:
| DDR5-6000 is 60GB/s per channel.
| mikepurvis wrote:
| Such a simple motherboard could even just put the power
| supply onboard, with a barrel plug or something, similar to
| how routers like this are configured:
|
| https://www.mini-box.com/Alix-APU-Systems
| MrBuddyCasino wrote:
| They did this, nobody bought them.
|
| Also the RAM bandwidth just isn't there, and special mainboards
| with more memory channels eat up the cost advantage. And
| they're hard to cool.
| sliken wrote:
| I've had the same thought. They obviously know how to add
| decent iGPU and the required bandwidth in the PS5 and XboxX
| (and the previous gen).
|
| Does seem like they finally plan to do this with the AMD Strix
| Halo which looks to hit somewhere late this year or early next.
| mdasen wrote:
| Others have pointed out things like memory bandwidth, but I
| think there might be another thing: would people want it?
|
| Let's say that the CPU + powerful iGPU cost 95% of what a
| discrete CPU and GPU cost - but now you can't buy them
| separately, can't upgrade them separately, etc. You're less
| likely to get the mix of CPU and GPU that you're looking for
| since you can't select them independently. Why not just package
| the RAM with the CPU too? Apple's done that, but I think most
| people don't love that because it means they can't upgrade
| their RAM independently.
|
| It also places constraints on how good something could be.
| Let's say that you produce new GPUs every 18 months and new
| CPUs every 12 months. Well, now you need to synchronize them.
| If the new CPU is ready to go, but the new GPU is 3 or 6 or 9
| months out, what should your product releases be?
|
| By having them separate, someone can buy the latest AMD CPU
| even though the next-gen GPU is 6 months out. When the next GPU
| comes out, they can buy that and upgrade the graphics and CPU
| on different cycles. Syncing up different product cycles isn't
| always easy.
|
| I think the reason why is that they don't think there's likely
| a market. With things like a PlayStation or Xbox, it's going to
| (pretty much) have one set of capabilities for its 7-year
| lifecycle. You can integrate the CPU and GPU because there's
| only one buyer and because the CPU and GPU release have to be
| synced anyway for the console's release. With PCs, the release
| doesn't have to be synced and there are many buyers with
| different priorities.
| roenxi wrote:
| I don't think they are reluctant, their APU have started low
| end and been steadily [0] moving up to the performance
| spectrum. We're about on schedule for some powerful ones to hit
| the market. The 8000G is the first that has entered the
| conversation but I doubt it'll be the last.
|
| [0] https://en.wikipedia.org/wiki/AMD_APU
| Dylan16807 wrote:
| I'm not sure what you mean by "too late"?
| nfriedly wrote:
| I never really got the point of the Z1 non-extreme. If it enabled
| them to ship a device for $400 or less then it would make some
| sense as a Steam Deck competitor, but not when the Z1 ally was
| $600 and you could double the performance by going up to $700. (I
| know it's gone on sale for ~$450, but IMO that should have been
| the launch price, with sales putting it below $400.)
|
| Honestly, the whole Z1 lineup puzzles me a bit, since it feels
| like just a re-badge of the regular mobile chips with some slight
| tuning. If AMD was going to go through the effort of making a
| gaming focused chip, they should lean into that with more
| emphasis on the GPU side, and perhaps some extra cache or more
| memory bandwidth. Maybe even drop a couple of CPU cores. What we
| got instead just feels like a cheap marketing ploy.
| wtallis wrote:
| I'm not sure there was any special tuning or binning involved.
| I think Asus just bought special branding without having any
| influence on AMD's silicon roadmap.
| agloe_dreams wrote:
| All of this is weird personally. I think it is weird that the
| 7840u (Z1X laptop model #) exists in the first place. It has a
| wildly overpowered GPU for a mobile chip of it's type and while
| they quote a 28W TDP, the actual max-power draw is
| stratospheric for a U series (well over 50 watts). To be
| honest, I wouldn't be shocked to find out the Z1X internally
| came, as a concept at least, before the 7840u. Meanwhile, the
| Z1 is so wildly weak in comparison. It is only 1/3 the TFlops.
| nfriedly wrote:
| > _I think it is weird that the 7840u (Z1X laptop model #)
| exists in the first place. It has a wildly overpowered GPU
| for a mobile chip of it 's type..._
|
| I have a handheld with a 7840U (GPD Win Mini), and I love it.
| I suppose if it were labeled a Z1 Extreme instead of a 7840U,
| I'd be just as happy with it, so I can somewhat see where
| you're coming from. But also I think it's becoming more
| common to want to run "real" (non-gaming) workloads that can
| leverage a GPU on devices without a discrete GPU, so I still
| think it makes sense as a general-purpose part. (Also, I
| think the Z1 was an Asus-exclusive part, at least initially,
| so if there wasn't a non-exclusive variant, then I'd be stuck
| with something inferior.)
|
| > _...and while they quote a 28W TDP, the actual max-power
| draw is stratospheric for a U series (well over 50 watts)._
|
| The ideal TDP for that chip is around 18W, with diminishing
| returns after that. (I usually run mine at 7-13W depending on
| the game.) Beyond 25-30W, you get only marginal performance
| gains relative to the amount of additional power, so while it
| technically can use over 50 watts, it's clearly not designed
| for that and the extra performance isn't worth it when you're
| running on battery.
| wtallis wrote:
| The 7840U is the same die as the 7940HS. AMD only did two
| mobile processor dies this generation; Phoenix 2 is in the Z1
| and the larger Phoenix is in the Z1 Extreme, 7840U and
| 7940HS, among others. So they're doing a lot of product
| differentiation solely through adjusting power and clock
| limits, which is confounded by the leeway OEMs have to
| further adjust those limits.
| ip26 wrote:
| Special tuning today, custom silicon tomorrow. Maybe this is
| the MVP of handheld PC gaming.
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