[HN Gopher] What is PVTM? Or why your Rockchip RK3588 CPU may no...
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       What is PVTM? Or why your Rockchip RK3588 CPU may not reach 2.4 GHz
        
       Author : zdw
       Score  : 34 points
       Date   : 2022-07-17 14:10 UTC (8 hours ago)
        
 (HTM) web link (www.cnx-software.com)
 (TXT) w3m dump (www.cnx-software.com)
        
       | wmf wrote:
       | Ah yes, advertising turbo clocks as if they're base clocks. Sadly
       | this is neither the first nor last time this will happen.
        
         | MobiusHorizons wrote:
         | This smells more like an integration issue to me. The chip is
         | essentially throttling because it's reaching a high temperature
         | or low voltage threshold. It could just be a bad power supply
         | or the hot ambient temperature (28c ~80f) mixed with inadequate
         | cooling.
        
           | okennedy wrote:
           | The same thing happens on a lot of mobile devices as well.
           | It's the reason that mobile devices generally don't get
           | advertised with clock speeds. E.g., see:
           | https://dl.acm.org/doi/abs/10.1145/3032970.3032982
           | 
           | Unlike desktops, where CPUs from different quality bins are
           | sold at different price points (with different clock speeds),
           | mobile CPUs are simply run at different voltages to
           | compensate for quality differences. The resulting differences
           | in power dissipation end up creating different temperature
           | profiles, depending on which bin you happen to get.
        
       | geerlingguy wrote:
       | I love the comments debating over what chip specification should
       | be advertised... if a chip is stable at 2.2 GHz, and many are
       | unlikely to perform at 2.4 GHz, it should just be advertised as a
       | 2.2 GHz chip (despite many being able to perform better).
       | 
       | The BCM2711 in the Raspberry Pi 4 model B (even the older B0
       | revision) was clocked at 1.5 GHz by default to save on heat, and
       | for stability, even though most (in my testing, all I've ever
       | used) can run at 1.8 GHz without issue in most environments, and
       | 2.0 or more with better active cooling.
        
         | e3bc54b2 wrote:
         | Hi Jeff! Just want to say thanks for all the great stuff you
         | put out for Pi. It really helped me get mine going (after
         | keeping it in drawer for 6 months).
        
       | pengaru wrote:
       | Isn't the RK3588 an 8nm part? Seems odd that it'd have this sort
       | of issue at that frequency, no?
        
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       (page generated 2022-07-17 23:01 UTC)