CPU VDDA voltage ?

[madman7]

Does anybody know what CPU VDDA voltage is and what it does? I did some searching but never found a good reliable answer.

 

[redduc900]

Understanding All Voltage Configurations from the Motherboard - AMD Processors: VDDA
http://www.hardwaresecrets.com/prin...ltage-Configurations-from-the-Motherboard/995

CPU VDDA Voltage
http://vip.asus.com/forum/view.aspx...1&model=M3A79-T+Deluxe&page=1&SLanguage=en-us

 

[trents]

That second link doesn't seem to answer the question as the OP in that thread didn't experience any change in running CUP vcore after making the change as he expected after reading the other poster's explanation. Neither does the explanation given by the guy in that forum thread seem to match up with the explanation in the first link, which is probably correct but falls short in not offering any explanation of how increasing the voltage to the clock multiplier might make a difference.

One problem with these kind of things is that it seems different bioses use the same terminology to apply to different functions.

 

[BeepBeep2]

Sets voltage for the PLL (Phase-Locked Loop) in the CPU. That is the part that sets the multiplier/keeps frequency, just like the PLL SMD on your motherboard that sets the FSB/HTT Ref. Clock/BCLK

Oddly enough some people have been able to up the voltage to it to help with stability when boards do not have Load-Line Control/Calibration. That is what is seen in the second link. I've toyed around with it before and have seen possible small gains in stability (though no measurable voltage difference with DMM) but usually it should be left at stock (2.5v) and usually going over 2.7v will reverse any gains and should be kept under that.

 

[trents]

Thanks for that explanation, Sam. Gives some clarity.

 

[BeepBeep2]

Yep, same rail is listed on Gigabyte boards as CPU PLL Voltage.

I'm not sure about ASRock/MSI/ECS as I do my best to keep away from those brands.

 

[madman7]

That second link doesn't seem to answer the question as the OP in that thread didn't experience any change in running CUP vcore after making the change as he expected after reading the other poster's explanation. Neither does the explanation given by the guy in that forum thread seem to match up with the explanation in the first link, which is probably correct but falls short in not offering any explanation of how increasing the voltage to the clock multiplier might make a difference.

One problem with these kind of things is that it seems different bioses use the same terminology to apply to different functions.

Sort of what I thought. Nothing really did answer what it is. Thanks BeepBeep2 for the explanation. I've noticed lately that my vcore fluctuates from 1.478 to 1.499 with CPU-Z even though it's set to 1.4875 in the BIOS. I was looking for LLC in my BIOS but don't see anything. When I run Prime95, I've seen it drop to 1.469 so I was looking for a setting to stabilize it some.