necro-post
Using a 990FXA-UD3 Rev. 4.0 board, ver. F2 Bios
Phenom II X2 560 black
similar situation with a similar cpu
upgraded to the ga990fxa from ASUS M4A78LT-M, migrated the x2 560 cpu over from it.
On the ASUS board I could successfully unlock all the cores and oc it to a stable 3.8 on the default voltages. Passed memtest86 with no errors,12 hours prime95 small fft with no errors, 12 hours occt cpu test with no errors, complete the 3DMark11 full test.
On the GA board I can unlock the (one or) two extra cores and oc it to a 3.9 on default voltages. Still passes memtest86 with no errors, can run 12 hours on prime95 small fft with no errors (if it can make it that far without freezing up).
The problem is the system freeze-ups. With the cores unlocked (one or both - doesn't make a difference) the 0cct cpu test and the cpu testing portion of 3Dmark11 will lock up the system immediately. No BSOD. no reboot. just freeze. The system also randomly freezes. It can freeze-up anytime; during boot, within minutes after logging into the operating system, several hours later either sitting idle or during use. I have a dual boot system with Windows & and Linux; the random freezes happen in both OS.
I've cranked up the voltages as high as i dare go (1.55 vCore) and made sure the temps stayed low (i've never got it above 53c). I've tried overclocking, default clocks, under clocking, and went through the same with over/default/under voltages and the plethora of combinations, but to no avail. Unlocking the cores = random system freeze no matter what i've thrown at it.
With the two cores locked i can oc the cpu to 4.0 stable on default voltages and the thing purrs like a kitten and passes all the tests that would otherwise freeze the system up with the other core(s) unlocked, and there's no random lock-ups.
This chip lived its life on another board with absolutely no issues, but once installed on this board it can no longer perform to its full potential.
The rev 4.0 board is a nice solid piece of hardware, but the mediocre UEFI is probably to blame for this