Originally Posted by LAKEINTEL
I think BIOS sets the voltage based on the chip
You got that right. If I'm correct the CPU requests a voltage. In this case I will call it VID which the CPU tells the motherboard what voltage it wants. The motherboard then gives it that voltage or offsetted depending on user preference or default settings. Now when it comes to motherboards, not all will provide the same amount of voltage. There will be a slight variance or maybe even significant in rare cases, this is due to the circuitry in motherboards as some are very accurate on giving the correct voltage from BIOS to reading the CPU voltage directly using a multi-meter or reading CPU voltage in operating system via hardware monitoring software like HWinfo64.
For example on a system with a i5 2500K and a ASUS P8Z77-V LX:
- I have it overclocked to 4.3 GHz on 1.30v.
- I'm using a balanced LLC (Load Line Calibration) setting to get the voltage closest to desired which is 1.30v.
- When doing stress tests like Prime95, HWinfo64 reports that the CPU is requesting a voltage of 1.40v which is from the VID readings.
- The motherboard is sending it 1.30v in CPU voltage. This variance is due to my adjustment of the LLC (Load Line Calibration) so that it sits closest to my CPU voltage.
- Now if I left the LLC on Auto / Normal. It will probably get the CPU voltage to 1.4v on load even though I have it set to 1.30V in BIOS.
Correct me if I'm wrong.