I spent a week trying to solve BSODs in Windows 7 x64, memory errors in memtest and yellow marks in device manager for two SLI graphics cards on a board with auto settings loaded in BIOS.
All started after a BIOS update from F3 to F8. Loaded default settings. Windows was occasionally BSOD with no indication of the failure (using BlueScreenView) other than STOP errors (usually with a bug check code of IRQL_NOT_LESS_OR_EQUAL) in ntoskrnl.exe, which is rather unusual. Thought initially I had some problems in the drivers and activated the driver verifier. The driver verifier actually pointed to problems in the driver installed by the Gigabyte tools (that was expected to be honest) but in the end, after uninstalling them, I was still out of luck. It was erroring in the same place, sometimes in win32k.sys.
First of all, the memory problems. The tool here
http://www.memtest86.com/ (ver. 4.0) is not compatible with this setup. It'll blow up with CPU HALT errors, making me thing it was CPU/memory related. This one here however
http://www.memtest.org/ (ver.4.20) seems to be working though, and initially it was giving memory erros in any DIMM configuration (even with one stick placed anywhere, with or without an XMP profile). Alright, I thought, no problem, large X4 mem kits usually are a challenge for a motherboard, even though it shouldn't be like that (considering the mobo specs) but hey, we're living in times where quality/testing comes as a second priority. So I started to up the voltage for the QPI/VTT and IMC to 1.2V, and in the end the DRAM voltage as well, but just slightly. The memtest succeeded and I was happy.
Next off however, I started seeing weird behaviour in the graphics card department. The "Enable SLI" option was either not active, or it was active and after activating it and a reboot, the cards would display a yellow mark icon in device manager and the resolution was lowered to a minimum. Reinstalling the drivers would solve the problem, but just for the current session. Imagine that happening on every single restart and you'll go mental too.
Now I was aware that I was kind of at the limit with the PSU (Thermaltake 700W old generation), giving lower amps on the rails comparing with the current generation, and I was just about to order one when....
... in desperation I short-circuited the Clear CMOS pins and great was my surprise that by loading defaults in BIOS I got a steady smooth running machine, even with the XMP profile turned on.
What gives Gigabyte? Do you like torturing your customers?