Asrock 970 Extreme3 motherboard
AMD Phenom ii x4 960t black edition
550w Coolermaster power supply
EVGA GTX 560 SUperclocked 1gb
500GB 7200 RPM HDD
Kuhler liquid cooling on CPU
windows 7 home premium(not pirated)
My problem...I had a athlon iix2 in mysystem. it was overclocked a bit and when I replaced it I forgot to reset the bios(am I supposed to? first time upgrading cpu) and it wouldnt boot up right after I installed the 960t. After I reset the bios to defaults I could boot up normal but if I changed anything in the bios it would reset the computer to make the changed take effect then it would be like I didnt have a video card plugged in...nothing on the monitor. the fan and stuff were going but nothing on the screen. after updating bios(well...reinstalling. it was updated) I was able to overclock somewhat but if I turn on UCC(I have run UCC before and it worked fine on the athlon...didnt do anything but it still booted and overclocked with it on). When I turn UCC on now to try and unlock the 960t's cores it resets to make the changes then makes it like there is nothing on the screen and I have to clear cmos to get anything to work again.
I reseated the cpu, ram, video card and cpu cooler and it didnt change anything. I also ran prime 95 and the 4th core failed for prime 95. turned it off and reran prime 95 and it was fine. don't know if that has anything to do with it.
I've narrowed it down to either the CPU or the motherboard. I'm hoping it's the CPU because I can return that, I don't have the original box for the motherboard anymore and asrock charges money to fix stuff even though it's only a month old.
I have the 970 Extreme4 with Phenom II 960T CPU. I had one instance of the what you speak of. I don't game nor overclock but have opened the CPU up to 6 cores by enabling the UUC in the BIOS you mention.
I was of course a bit unsettled by the fact that the computer would boot...get the single beep...no codes and yet nothing on the screen. I have the UEFI BIOS 1.50. First thing I did was yank my 8gig of memory...no change. Rechecked all connections. No change. I started to suspect the Saphire Video card....since the issue was no video and yet the machine seemed to boot normally...just nothing on the screen. Pulling the video card...its in a PCIe slot and reinserting it seemed to fix the problem....but not convinced this was the root cause.
I will tell you what I suspect however and it pertains to what you wrote...the UUC in the BIOS and opening up the 960T CPU to 6 cores. I have CPU-Z freeware that shows how many cores are active. My machine inexplicably boots with either 4 or 6 cores...without rhyme or reason...sometimes 4, sometimes boots to 6 cores...with the UUC enabled in the BIOS. So...I believe there maybe an issue with opening up the 960T CPU aka enabling the UUC setting in the BIOS...sometimes it opens up 6 cores and if it tries to without success and stumbles...no video. This is just my opinion.
If running the 960T with ASRock mobo, perhaps best to not unlock the extra 2 cores...or only do so if using the computer for heavy gaming applications.
i have an 870 extreme3 that behaves similarly when i turn on ucc with an x3 phenom ii. im pretty sure it stumbles trying to unlock the extra core and dies. i got around this by disabling ucc (no extra core boo) and manually setting up the rest of my overclock.