VCore Voltage Fluctuations

[marks70]

I just built a new PC around an A64 X2 3800. I also bought a new Seasonic 500W power supply. When monitoring the voltages in both the BIOS and Windows, I noticed that the VCore voltage is constantly fluctuating, between 1.36 and 1.42. The Seasonic is supposed to be one of the best power supplies out there, so does this mean there is something wrong with it? Shouldn't the voltages not fluctuate at all assuming you're using a good power supply?

 

[FlyingPenguin]

Voltage should be within 5%. For the 3.3 volt rail that's between 3.13 and 3.47.

HOWEVER onboard voltage monitoring is notoriusly unreliable. Only way to know for sure is to use a digital multimenter (around $20 at Radio Shack) and measure the voltage across the 3.3 volt lead on the mobo PSU connector (orange wire) and ground (the metal case or any black wire on the mobo PSU connector).

If it's consistently over 3.5 volts using the multimenter then I'd be concerned.

 

[marks70]

Hi,

Sorry, I screwed up on what I originally wrote. I meant to write the VCore fluctuates between 1.36 and 1.42 - I've corrected it. Is the 3.3 volt rail where the CPU gets its power? My 3.3 volt rail looks pretty solid at 3.35V, so what would cause the voltage fluctuation in the VCore so much?

 

[FlyingPenguin]

Those voltages aren't out of line for vcore - depending on what you have vcore set to in BIOS. Just calculate 5% of the vcore voltage setting you're using and see if you're within spec.

Vcore is not generated by the PSU directly. It's generated on the mother board by a regulator. Not sure if it's regulated down from the 3.3 or 5 volt. Probably the 3.3 bus.

 

[marks70]

Thanks a lot for your response. Good info!