For the first time in a long period I've decided to switch my motherboard brand to get the GA-Z77X-UD5H because it seemd a better bargain than other competing products but I'm getting a bit disappointed lately, specifically concerning OC capability and stability as I'm running into multiple issues with this board.
First, here are the build specs :
16GB DDR3 PC3-12800 Patriot PGD316G1600ELK
XFX 6850 HD-685X-ZNDC (using Accelero S1 Plus cooler).
Corsair HX520 PSU (3x18A) changed for Antec High Current 620W (1x48A)
Case is Antec P182.
So I get all of the pieces, build it up, upgrade the UEFI to F6 (back in the days) and then get started on O/Cing it with the original PSU I had.
Fairly quickly I get the CPU really stable at 4.5Ghz with the following settings : 100mhz Core speed, 45x mult., 1.190v Vcore, "Extreme" Vcore Current Protection and "Extreme" Vcore Loadline Calibration (i.e. no vdroop), disabled the C3/6 state and forced the "Turbo" mode to 45.
This setup allows me to run prime95 stable for hours, CPU reaching temps of max 80-82°Celsius (one core), while other cores are between 70° and 78° (the 10° difference between cores really surprises me).
All seemed good and well but then I wanted to see how the temperature of the GPU would affect the CPU's in order to gauge the case's cooling efficiency. That's when things turned ugly.
As soon as I started Furmark I got a BSOD.
Then the UEFI wouldn't POST normally, it would try to POST twice, stopping on error code 15 (Northbridge init.) and then reboot get back to the config screen telling me either that it had a boot failure or that I could revert to "optimized defaults".
Immediately I tried to find out whether it was a video card problem so I ran Furmark alone again and to my big surprise it didn't crash for about an hour (temperatures are fairly reasonnable, solely reaching more than 70°).
I figured that maybe the video card was pumping too much juice on the rail, so I tried switching rails, switched to another video card (8600GT), yet the same thing happenned all over. It would crash and then boot loop.
Between all the tests, I noticed that whenever I shut down the computer completely and cut the power for a couple of minutes, I was able to POST with the OC settings w/o problems or boot loops (as long as it hadn't already tried
to POST and failed, otherwise it sortof continue failing until I saw the UEFI "boot problem" screen).
I thus upgraded the UEFI to F7, put back the 6850 and did the test again but to no avail, it would still fail. I tried raising the vcore to 1.2-1.25, nothing would make any sort of difference, it would crash and then boot loop.
I also tried changing the core speed to 100.1 or 101, although it would help some of the POSTs, I still could not run both burn-in at the same time.
The next option was to look at the PSU, so I got a new one, single rail (just to make sure that wasn't an issue), and almost immediately started the CPU+GPU bench at 1.190v vcore.
The surprising thing is that it worked for about 20min, but then the same issue happenned (actually I had no BSOD but prime95 just crashed) and when I rebooted this time I got an even worse boot loop, it would do it forever.
I upgraded the UEFI to F8D just for the sake of it, then unplugged everything, waited a bit then got it to POST and I decided I would be changing some other UEFI settings.
Since it looked like a voltage problem, I lowered the vcore protection and vcore calibration to "high" instead of "extreme" and went back to try and find the stable vcore voltage for my 4.5ghz OC.
After being able to run prime95 stable for hours using a 1.24 vcore (vdrooping to 1.20 under load), I decided to run Furmark in parallel and successfully got it to run for about 45mins before prime95 crashed.
So now, I guess my only options left are to lower the vcore voltage tightening and raise the actual vcore but to me it seems a bit stupid for the board to provide me with super-tight voltage reg that aren't able to sustand high loads...
Does it seem like some voltage regulators might be defective ?
Does anyone have other suggestions ?
Thanks for the help !