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Z690 Apex set voltage way off from reported voltage in bios

TresNugget
Level 7
At llc 4 with 2 different 12900K CPUs, when I set manual vcore, the reported voltage in the bios is .06-.08v off. For example, if I set manual vcore to 1.4v, the bios reports 1.32v. If I set 1.5v it reports 1.42v If I set it to 1.3v the bios reports 1.24v. With other boards I've seen .02v-.03v like 1.3v reporting 1.279v. It's like I'm getting vdroop in the bios. Has anyone else seen this?
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3 REPLIES 3

Silent_Scone
Super Moderator
Hello,

The BIOS puts a small load on the CPU. Check with HWinfo or other reporting tools, making sure to look for Vcore and not rely on CPU VID. Is there any reason you're using a manual vcore over adaptive or AI OC? If checking against the enclosed Voltician you'll find that the die sense is close or near identical to the actual voltage.
13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090

Silent Scone@ROG wrote:
Hello,

The BIOS puts a small load on the CPU. Check with HWinfo or other reporting tools, making sure to look for Vcore and not rely on CPU VID. Is there any reason you're using a manual vcore over adaptive or AI OC? If checking against the enclosed Voltician you'll find that the die sense is close or near identical to the actual voltage.


I couldn't get AI OC stable, and I've had bad luck with adaptive in the past not behaving as expected. I usually use manual then set with offset. Looked at buildzoids apex video and he's set at 1.43v getting 1.403, same with a friend of mine. His set vs what's reported is also about. .03 off on his z690. But I might have to check with that as this is making me not trust the die sense. I don't see why there's a huge step down from what the vrm is sending to what the die sense in the bios is reading.

TresNugget wrote:
I couldn't get AI OC stable, and I've had bad luck with adaptive in the past not behaving as expected. I usually use manual then set with offset. Looked at buildzoids apex video and he's set at 1.43v getting 1.403, same with a friend of mine. His set vs what's reported is also about. .03 off on his z690. But I might have to check with that as this is making me not trust the die sense. I don't see why there's a huge step down from what the vrm is sending to what the die sense in the bios is reading.



As already said the UEFI puts a load on the CPU.

Adaptive voltage behaviour can be misunderstood easily as it still needs to work in conjunction with Intel design. The applied voltage is easily manipulated however by using the SVID behaviour function, trimming AC loadline settings or VF Curve tuning.
13900KS / 8000 CAS36 / ROG APEX Z790 / ROG TUF RTX 4090