Asus PC Probe Accurate ? My C2D Vcore Varying ...

[Midnight Rambler]

As noted, my VCore reading in Asus PC Probe II is varying, anywhere from 1.14 to 1.28v. My BIOS reports otherwise.

Intel C2D E6600 at stock settings on an Asus P5B-Dlx with Zalman 9500 (plus AS5) and a Corsair 620W PS which is rock stable. Temps are great, 18-20C@idle per Core Temp.

Thanks !

Update : CPU-Z also shows variation but only in the range from 1.136-1.160v

 

[Boyo]

It will show a variation. It is just a normal part of your mobo for the voltages to vary slightly. No big deal.

 

[wgoldfarb]

The voltage variation is probably caused by C1E being enabled in the BIOS. C1E effectively lowers the multiplier of the CPU when the CPU is idle, to allow it to consume less power and stay cooler. So, when your CPU is idle, the multiplier and frequency drop and Vcore follows (if you monitor Frequency and Vcore with something like speedfan you will see what I mean -- the E6600 frequency drops to 1600 --multiplier of 6-- when the CPU is idle). When the CPU is under load, multiplier goes back up, and Vcore follows.

If you want Vcore to stay constant, disable EIST and C1E in the BIOS. However, there is a benefit to having C1E enabled, in that the CPU will run much cooler when idle.

 

[Binky]

18C-20C? You sure about this?

 

[RonAKA]

I see the voltage drop as CPU usage goes up.

 

[Midnight Rambler]

BIOS says 26.5

Core Temp says 19 and 21

And I have come to the conclusion (again) that Asus PC Probe sux. I got fooled in to thinking since it was rev2 it might work right (1 never did).

I miss Motherboard Monitor 🙁 , it usually was very close to BIOS readings.

 

[wgoldfarb]

I was having problems with inaccurate and inconsistent temperature readings in my P5B Dlx with Speedfan and TAT, until I went into the BIOS and enabled ACPI 2.0 support and PECI. I am not sure why this worked, but it did. I am also not sure which of the two did the trick (I haven't gone back to turn off just one) but I suspect it was ACPI 2.0 support. Once I did that my temperature readings were much more sensible.

By the way, there is an outstanding guide to Core 2 Duo temperatures at Tom's Hardware (disclaimer: I am too much of a noobie to be able to tell if the guide is accurate, but the author seems very knowledgeable). It explains the difference between "CPU temperature" (read by the BIOS, Asus Probe and Speedfan, among others) and the "core temperature" read by TAT and Speedfan. It also provides guidelines for acceptable values for these temperatures when idle and while under load. As a noobie who just built his first rig, I found the guide to be an excellent resource to help me navigate the "soup" of Core 2 Duo temperatures.