Originally Posted by Nighthog
All new BIOS limit VCORE @ 1.500V tops and that's why I presume we aren't hitting the BOX /advertisement speeds.
I have found, at least in my 3900X, that isn't really true. It seems to me, that the problem lies with some other internal limiter, or perhaps the precision boost algorithm itself vs the actual silicon.
You can read through my testing here. https://community.amd.com/message/2927615
But to summarize, I ran my 3900X in a Cinebench R20 and like so many others noticed a top clock around 4.5 with precision boost, and a voltage applied of about 1.48V. Cinebench R20 single thread score was 509 in that setup. So I was curious if it really was the silicon or the boost itself.
In UEFI, I disabled "Core performance boost" altogether so the boost algorithm was taken completely out of the equation. Using Ryzen Master, I then set just my fastest core to 4.6 GHz, leaving the others at 3.8 GHz. I upped the VCore to 1.48 to simulate exactly the voltage and clock speed thresholds used by PB. Using process lasso, I then set Cinebench to only use the fastest core, I did this partially to prevent core jumping, but also so that if I accidentally hit the all core test, it wouldn't try to launch it with a 1.48V Vcore.
The result, In Ryzen Master, was that 4.6GHz was hit and maintained the entire test. Not only that, but the score improved to 524 in Cinebench R20, indicating this isn't just a clock stretching phenomenon. The silicon can do those clockspeeds, and what's more, it can do it with the voltages PB is already applying. Just when PB is allowed to do manage the boosting, it is trying to use vastly more voltage than necessary.
In the first part of my test, I set my Vcore equal to 1.3V (the maximum I saw PB use on an all core boost) and then overclocked the CCXs manually using Ryzen Master. I set CCX0 of CCD0 (contains the fastest core) to 4.5GHz and ran the Cinebench R20 single threaded test, again using process lasso to tie the thread to core 02. I got a score of 508. This is virtually identical to the 509 I was with precision boost, which I would expect since the clock speed was 4.5 in both cases. The difference was, I did it with 1.3V manually, while PB felt the need to apply 1.48V to do the identical amount of work.
So it seems that the algorithm itself is to blame here, it seems to apply vastly more voltage than is needed to do the amount of work being asked. Now it is possible that there is some sort of other internal limit at play here. Voltage, in and of itself does not generate heat, only when current is applied to do actual work does heat come into play. Maybe at 7nm, there is a per core power limit that has been applied, and PB regulates the frequency at the boost voltage to ensure that is maintained. That limit is then ignored during manual overclocking. Hard to say for sure, but I can say that the voltage being applied today is good enough to hit the boost clocks on my chip, just precision boost won't go there.