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Asus P6T question: Very low vcore

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March 19, 2009 10:48:50 PM

Hello, I have some strange issues and needing some opinions. I'm building 3 systems using Asus P6T and i7 920 and currently built 2 of them. 3rd one is on hold as I had to RMA it. Of the two I built, one is supposed to be a workstation and the other is file server/render system. Here are the specs

Workstation
CPU: Intel i7 920
MB: Asus P6T (X58)
RAM: Corsair XMS3 6GB (3x2GB) DDR3 1600
PSU: Corsair 550VX (550Watt)
Video: EVGA GeForce GTX 260 896MB
HD: 2x Western Digital Caviar Black 650GB in RAID-0
Optical: LG 6X Blu-ray Burner
OS: Vista 64 Business

File Server
CPU: Intel i7 920
MB: Asus P6T (X58)
RAM: Corsair XMS3 6GB (3x2GB) DDR3 1600
PSU: Corsair 550VX (550Watt)
Video: Biostar GeForce 9400 GT 1GB
HD: 4x Western Digital Caviar Black 750GB in RAID-10
Optical: Samsung DVD Burner
OS: Vista 64 Business

So everything is same except the RAID array, Video card and Blu-ray/DVD burners. But the server vcore shows 1.204v and workstation shows 1.03v in the BIOS. In CPU-Z server is 1.19v and workstation at 0.98v. BIOS and all drivers are latest and nothing tweaked in the BIOS except XMP mode to take advantage of DDR3 1600. Everything else set to default "Auto" Vcore difference exist even without XMP mode as well.

To me, the workstation vcore seems way too low. I thought 1.25 is the default? The workstation's core temps are much higher as well. Server stays low 40's but workstation hovers at around low 50's. But strange thing is that the workstation is more stable. It's been 2 days since I built them and the server has BSOD'd 3 times already and the workstation never crashed once. Another difference I saw in CPU-Z was that the workstation's QPI link was at 3200MHz and server was at 2400MHz. Have no idea why this is.

I was able to enter the vcore manually in the BIOS for the workstation to 1.2v so I'm pretty sure it's the motherboard lowering it and not issue with PSU. But when I manually entered 1.2v in the BIOS, the core temp rose to 60's.

Right now, my guess is that the HSF is not mounted properly and the motherboard is lowering the vcore in attempt to lower CPU temp. I thought I mounted both of them properly but I am going to try re-mounting the HSF tomorrow with arctic silver (right now it's with stock thermal goo) but in the mean time, I would like to know if anyone has any other theory. Because while searching, I found this other Toms hardware forum post who also posted CPU-Z screenshot with fairly low vcore as well but no one seemed to point it out as a problem so vcore around 1.0v is normal with P6T? Then why is my server at 1.2v? Getting more confusing.

http://www.tomshardware.com/forum/251463-29-learning

And even if the HSF is the cause, I don't think it explains why other settings are different. Besides the QPI Link difference, DRAM timings are different as well. Workstation is set at 9-9-9-24 and server is at 8-8-8-xx (forgot the last digit). When set to "Auto" why is this motherboard configures similar system so differently? Is it because the workstation has bigger graphic card which sucks up more power?

Please enlighten me as I have built many systems before, but this is my first time building i7/X58 system.
a b V Motherboard
March 20, 2009 12:11:01 AM

Different CPUs have different voltages at default, even if they are the same model number. It depends on how it is set from the factory. Unless you have stability problems, there's no reason to be raising it from its initial 1.03. For example, my i7 965 runs anywhere from 0.92V to 1.13V at stock clocks, depending on what speed it is running at (with speedstep and turbo on), and it is easily capable of full 3.2GHz operation on 1.08V.
March 20, 2009 3:02:25 AM

Thank you for the reply. That makes me feel better :)  But what about the difference in QPI Link or the DRAM timing? I mean... it's exactly same motherboard and same RAM, why would it be different when set to Auto? Should I manually set these values or leave them auto as well? What are default values? I assume 133 for QPI Link? As these are for business, I'm not looking to overclock.
Asus forum is down for the whole day. It's frustrating.
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