BSOD After Multiple Changes, More Prevalent While Playing Games?

A while ago my USB ports came detached, and a few days ago my last one finally broke off. I called Dell Tech Support asking for a number, and the person on the phone insisted on using remote access to uninstall/reinstall/install drivers for me, despite the fact that the USB drive itself was rattling around insidehey then sent someone out to replace the motherboard. After the MB was replaced, I immediately plugged in my brand new 2TB external hard drive, and copied all of my .iso game files. After that I started getting random shut downs with no warning, no freezing, and no blue screen. I would be using my computer, and all of a sudden it would be turned off. At the time, I'm pretty sure I was playing Sid Meiers Civ 5.

I called Dell back, and they said they would send someone out to replace the motherboard again. I called on Thursday, May 3rd, about an hour after the guy who replaced my MB for the first time left my house. Later that night, my computer started freezing up, with audio stuck on repeat in a half second loop or so, and I would have to shut it down manually. Then it started BSODing.Today (May 8th) they replaced my MB, Heat Sink, and Fan. This time I was able to play Civ 5 for about 10 minutes before it blue screened. I then transferred the .iso file to my computer instead of my external, and I was able to play for perhaps an hour, hour and a half before it blue screened.