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View Full Version : Really unstable Vcore on XFX 790i


xaviondk
06-11-2008, 09:53 PM
Hello everyone.

I have gotten hold of a XFX 790i and a Q9450 plus some OCZ DDR3 GOLD RAM. And everything is running really nice.

So far i got my Q9450 up to 3701 Mhz, prime stable for 8 hours before i stopped it.

But it worries me that this 790i motherboard has a huge Vcore drop under load. I did update to the latest P05 BIOS. And put the Vcore at about 1.39 in BIOS. Which shows up as 1.35 in CPU-Z. But as soon as i start running Prime, the Vcore drops to a stunning 1.29 / 1.30 V. And even lower to a 1.28 when the CPU gets close to 80 celcius.

Is it a bad designed motherboard, or do i have a crappy PSU?

Im running with a CoolerMaster 620W. I cant remember which model, but it is one of those where you can remove the cables you dont need.

Any suggestions for a more stable Vcore?

http://peecee.dk/uploads/062008/overclock.PNG

Regards
Xaviondk
Oliver
06-12-2008, 12:58 PM
Its common with 790i boards...
xaviondk
06-12-2008, 02:05 PM
Okay. :-/

That sucks a bit.. It drops almost 0.6 V under load. Thats a freaking lot.

Btw i just tried 3800 MHz, booted fine and ran fine in windows. Didnt have time for stress test though. This Q9450 is a lot more fun then my old E6600. :P
aspire.comptech
06-12-2008, 04:07 PM
You cpu should not be hitting 80C...
xaviondk
06-12-2008, 08:50 PM
I ordered a new CPU cooling kit. It seems like the LGA775 mounting for my Thermalright XP-90C isnt that good.
T_M
06-12-2008, 11:28 PM
vdroop of that magintude is pretty common for all motherboards without specially designed anti-droop
xaviondk
06-13-2008, 12:14 AM
Thats some sad news, considering this is not a cheap motherboard.. Also its an XFX product. Thought it was an enthusiast brand, so they would have included such a feature. Mid-range ASUS has that feature for crying out loud.
T_M
06-13-2008, 04:26 AM
They also custom design their boards and bioses...
YMAA
06-13-2008, 04:29 AM
vDroop is part of Intel's specification for LGA boards. Asus, Foxconn, DFI, etc. make non-reference boards that have features like LLC that reduce vDroop. Look around for a vDroop mod on your board and see what you can turn up.
xaviondk
06-13-2008, 05:39 AM
Any idea where i can find a guide to such a mod..

The only one i can find is for 680i, or unconfirmed ones for 790i.
Deanzo
06-14-2008, 01:08 AM
This link has the vdroop mod in it http://www.xtremesystems.org/forums/showthread.php?t=181677

Under 1.6 volts the mod works very well, over that you have to back off to get it to boot. With the mod on the board I couldn't go any higher than 1.87v in the bios, with out it I could set all the way to 2volts in the bios.
I don't understand how or why, but it's like it kicks in OVP if you lower the resistance to much on mid to high vcore.