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post #3420 of (permalink) Old 09-24-2018, 01:46 AM - Thread Starter
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Quote: Originally Posted by majestynl View Post
hehe that explains a lot ! Lol.. i knew it wasn't something with bios settings. Anyways.. Thanks AGESA for spending hours !

Just to be clear... this means there is no downvolting opportunity for Pstates OC anymore! ?
I think this situation calls for further explanation.

On Ryzen CPUs, at least currently, there are 3 different P-states with different FID/DID (frequency) and VID (voltage). When the frequency is increased above the default base frequency (for example 3.7GHz on 2700X), the CPU will enter "OC Mode" which disables any power limits, CPB, XFR etc. In recent AGESA versions, "OC Mode" also prevents the CPU from requesting a lower VID than what P0 is set to. This means that the CPU will keep switching between the different P-states with different frequencies, but the voltage will be fixed at the P0 VID.

On top of this, there are also C-states. C-states are deeper power saving states which triggers functions like clock gating essentially turning off cores or other parts of the chip. If the chip enters a state where all cores are turned off, the CPU may also request the Vcore VRM output to turn off momentarily. This happens within milliseconds (maybe even microseconds, have not measured it) and is not noticeable to the user. What you will notice that the the reported CPU Core Voltage will read very low values around ~0.4V, which is an average value. If the CPU Core voltage is 0V for 1ms, then ramps up to 0.8V and stays there for 1ms, the average reading will most likely be around 0.4V.

It's still possible to use C-states while in "OC Mode", which means that you can still have some power savings and something that looks like "downvolting" while overclocked. To enable C-states, set AMD CBS\Zen Common Options\Global C-state Control = Enabled in BIOS. A side note on this is that when the CPU requests the Vcore VRM to turn off, it can reset any fixed override voltage that's been set. This means that you should not use Global C-state Control together with Vcore in Manual Mode.
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