I bought a refurbished M2A-VM from geeks.com to replace an ECS board. My computer on the ECS board worked fine except one of the on-board USB ports was not working and I wanted a board with on-board DVI.
So after I moved everything over to the M2A-VM board it starts crashing a lot. It would fail Prime95 after 10 minutes. I increased the NB and SB voltage and DIMM voltage, both +0.1V, and it seemed to stabilize and there are no errors in Prime95 for a couple of hours.
I thought I had the problem fixed but a week go by and the video scrambled up and the computer restart itself. I ran prime95 after it booted up again and it found errors within the first minute. I restarted the computer a few more times without changing any settings and it seemed to be completely stable again. But after a few days, it still crashes. A lot of times, the video would scramble right before it reboots itself. I've tried upgrading and downgrading the BIOS with no luck. I ran memtest86, chkdsk without detecting any problems. I don't even think voltage is the problem now because I've tried resetting the BIOS settings to default and sometimes it would appear to be completely stable for a few days but still ends up crashing.
The only hardware change I made from my previous system is the motherboard and an added USB 3.5" internal card reader. Since I did not have any of these issues on my previous motherboard with almost the same hardware, would it be safe to assume that the motherboard is defective?