BSODs and Random Reboots

Hey guys. I've had problems with my sister's computer for months just randomly rebooting, but we didn't care all that much because she got a laptop.

I'm firing this puppy back up and trying to figure out what the problem is. I thought it was RAM at first, because it was running pretty well with one stick, but eventually it rebooted, and still does. I've tried both in Single channel mode, in dual channel mode, and in different slots. The system stays up longer with one stick in and in dual channel mode, reboots sometimes before Windows even boots up. I did a memory test on one of the sticks by itself with memtest86 and it passed with no errors. I've changed the voltage from Auto to 1.8V to 2.1V, and doesn't help.

I attached 2 dump files. and maybe someone can read them for me and see if it says anything. The first time was a MEMORY_MANAGEMENT bsod, the other one was a 1E. There was a time before that where I got something that said IRQL_LESS_OR_EQUAL I think, but didn't get a dump file for that.

Help would be greatly appreciated!