Computer freezes\Won't start back up\CMOS Checksum
This has been an ongoing problem since I got my new motherboard. I got back from a trip to find my motherboard dead, it wasn't starting up, so I got a new motherboard, reformatted, and it would work for an increasing amount of time each time(meaning the first times I used it it would just shut down after say 5 minutes, then 10, then 20, etc). I took it to Geek Squad, and they couldn't figure out what the problem. I took it home and eventually I got it working again fine. Then as that ceased to be a problem, it would freeze up, and have to be manually shut off by the switch in the back. Trying to start it back up, I'd get one long beep, which I believe is a memory error. So I mess around with the cmos jumper and battery a couple times, try and start it up, and eventually it will start up. When it finally does, I get a "CMOS Checksum error- CMOS Cleared"(or something like that).
If it actually starts up, I have to keep working it up as far as uptime, or else it will freeze and have to do the same process over and over again. But always it eventually freezes up, and it takes a days worth of messing around with the cmos jumper to get it working. Last time it worked, I put alarms on the power and temperature meters, because I thought it may be a power problem, but nothing came up, and the next day after I turned it off, it wouldn't start back up again until I fiddled around. Any help?
Note: Putting the new mobo back in, it wasn't the same size as the old one, and there's now a 4-pin connector coming from my power source which is not used. I asked at the Geek Squad if this may be the issue from before, but they said it wasn't anything that would be causing the problem.