Incorrect Vcore values on Asus P5B???

[wgoldfarb]

The BIOS Vcore settings on my P5B Mobo do not seem to work. When I set Vcore to Auto with C1E enabled, Asus probe and speedfan show Vcore at idle of 1.14, increasing to 1.27 under load. So,I tried disabling C1E and setting Vcore manually to 1.275 (the option closest to 1.27), but when I check Vcore (with Speedfan and with Asus Probe) it is 1.24V, not 1.275V. If the CPU is under full load (100% using TAT). Vcore drops slightly to 1.22V.

What gives? Is this normal, is it a problem with the BIOS, or do I have a defective MoBo? Should I worry? I don't think it is a PSU issue, as the PSU has no problem delivering 1.27 V when Vcore is configured as auto in the BIOS.

I have the Asus P5B deluxe, Core 2 Duo E6600, Corsair HX620 PSU (the rest of my specs are in my signature, below). The voltages reported by Speedfan are as follows:

Vcore = 1.24V
+12V = 12.04V
AVcc = 3.31V
+3.3V = 3.28

TIA

EDIT: I am running the latest BIOS (1004).

 

[wgoldfarb]

Ok, I have some more information:

I tried different BIOS Vcore settings, to see what actual Vcore values resulted. This is what I found:

BIOS...................Actual
Setting.................Vcore
-------------- ---------------
1.3000..................1.264
1.2875..................1.248
1.2750..................1.240
1.2625..................1.224
1.2500..................1.216

In all cases C1E was disabled, and the CPU multiplier was fixed at 9. The Vcore measurements were with teh CPU idle, as they were taken directly from the BIOS setup's "hardware monitor", without even going into the OS.

Vcore settings on this MoBo seem to be completely unreliable. Is this normal, is it something I am doing, or do I need to RMA this MoBo?

Anyone?

 

[Xvys]

I think what you are experiencing is "voltage droop", which is inherent with the P5B boards. I set the vCore voltage at 1.3875v, which is actually 1.32v (480FSB). Most of these boards suffer from a .6 to .75 voltage droop. There are many threads and posts about this topic.

 

[wgoldfarb]

Xvys,

Thanks, I tried searching but did not know it was called "droop" so I searched for "voltage drop" and found many unrelated threads . I will search for "droop" and read lots more on this.

I guess it is good to know that it is normal, yet disappointing to know that a board with 8 phase power would, on the other hand, have so much "droop". If they invested in giving the board 8 phase power, you would think they would have tried to get rid of this.

Thanks for your help! :beer:

 

[Xvys]

yep, I am surprised the Deluxe with it's 8-phase design would also droop so much. I think other manufacturers suffer from this also. The P5B is still a great board, but o/c'ers must boost the vCore voltage accordingly to accommodate this. Mine is just the base model, but it is very stable at high o/c and was bug-free from Day 1...which is more than I can say for the DS3 I owned for, 1 Day...then returned it for the P5B

 

[wgoldfarb]

Yes, I am very pleased with the P5B. This is my first build so I have no reference to compare it to, but it made the build very easy and trouble free. The MoBo posted at the first attempt I got the Deluxe in part because of the 8 phase power, so I was very disappointed to find out about this "droop", but I guess every board has its quirks, and now that I know this is "normal" I'll stop worrying about it.

Thanks again!

 

[Xvys]

Besides the 8-phase design the Dlx has many other features which are probably worth the extra money, like better heatsinks and cooling solutions, more control over voltages, Raid, Firewire, ect, which are absent on the base model.