What's holding back my voltage?

[overCee]

I set up a system last week and have had it running 24 hour+ Prime95 stable at 334x9 at stock voltage (1.2875v). I tried to boost that up to 355x9 this morning at stock voltage and got a prime95 error almost immediately. Then I raised the voltage in the BIOS to 1.2975v and also got a Prime95 error in about 25 minutes.

I have noticed both with CPU-Z and the uGuru utility installed that the voltage at idle was running at about 1.25-27v and at load it was running about 1.22-23v at full load. I realize the load drop is vdroop, but why is the idle voltage so much less than it should be? Are CPU-Z and uGuru bad at reading voltage, or is something in the system lowering it? C1E and Speedstep are both disabled in BIOS. Temps are less than 60C at full load using Coretemp.

Thanks for your help!

Q6600 G0 w/ Tuniq Tower 120 cooler
Abit IP35 Pro w/ Bios 11
2x2GB OCZ Vista Upgrade DDR2-800 running at Auto and 1:1 ratio
XFX 8800 GTS 320MB XXX edition
Corsair 620W PSU
320 GB Western Digital HDD

 

[genec57]

There is no problem with the voltages being reported. You just need more vCore to support the higher fsb.

 

[SerpentRoyal]

Enable C1E and EIST. These will help lower Vcore and CPU speed when PC is idling. Raise Vcore to 1.36. Bump FSB to 340MHz and test for system stability using Orthos Large mode (10 min) and Memtest86 test#5 (10 loops).

OCZ RAMs are not very good. Manually set Vdimm to 2.1V and timing to 5-5-5-15. I guess people buy them cause they are cheap AR.

 

[overCee]

If my voltage is set to 1.2875 or higher and being reported as less than that at idle, how is that not a problem?

Also, if the RAM is set to auto everything, and running at a lower speed than it's stock speed, that is unlikely to be the problem right? I did test it thoroughly with memtest86+ when I first got the machine together. Why would I enable C1E and Speedstep before the system is demonstrated stable without them?

 

[SerpentRoyal]

There will be a small voltage drop when idling and under load. All P35 boards have vdrop/vdroop. The goal is to enable C1E and EIST to further reduce voltage when idling. If you need 1.34Vcore under load for stability, then dial in 1.38-1.40 in BIOS. The MB will never see the higher voltage.

C1E and EIST do not affect stability at default CPU multiplier.

Need to test RAMs at the new overclocked settings.

 

[overCee]

Got it. I had not realized there was a drop of voltage from the specified value when the system was idling.

 

[bryanW1995]

yeah, it is kinda annoying. high end asus p35 mobos have a setting to regulate vdroop, all others suffer.