BSOD, Computer restarts, then only half ram

My computer has recently developed a BSOD problem. I've been using the same hardware for a little over two years now, but recently my computer has started BSODing. After leaving it off for a certain period of time, it will BSOD (rather randomly) after startup. It starts right back up, but then half of my ram is system reserved. It never BSOD's after the first one. The most common time for it to happen, is when I'm playing a game, watching a video, or extensive multitasking. I have HWmonitor running to check temps, and it only does it once, so I doubt it's that.

I'm not an expert, but I think it's motherboard failure. Just want some impute before I take the plunge.

Regrettably, I was unable to find it. It didn't bsod today. The next time it does I'll get the minidump file and post it here.

After getting the debugger and looking at my minidump file it says that it is partmgr.sys, so I ran a chkdsk on all my drives. They came back good. Did a memtest, that came back perfect as well.

I did notice there was an update to the firmware on my ocz vertex2(I have 1.27 and the most recent is a 1.37). I find it a little odd that this is only happening now though. Anyway it's the firmware? The only other three things I can think of: CPU going bad, motherboard going bad, or (hopefully) a bad driver.

Note: I have, in the last 3-4 days, stopped playing Civilization 5 everyday. Since then, then BSOD has stopped happening. Again, I'm watching temps. Playing a little Might and Magic: Heroes 7, and the BSOD doesn't happen. I'd rather not mark this as solved, because I would like to play civ5 again, and I'd stake my typing hands that civ5 doesn't directly cause a BSOD.

This seemed to fix it. Thanks for the help.