HELP bsod

Okay, so here's the issue, whenever i walk away from the computer and don't use it for more than 20minutes, i start getting a bluescreen/restart. It then gives me reports like this:

BCCode 7a
BCP1 FFFFF6FC50033158
BCP2 FFFFFFFFC0000185
BCP3 000000011A5EB820
BCP4 FFFFF8A00662B9AE

OS Version 6_1_7601
Service Pack 1_0
Product 768_1

I've turned off screen saver and sleep mode, and it still happened. I ran sfc /scannow and it showed no problems. I ran chkdsk and nothing that i could tell was wrong--showed no issues. This only happens when the computer isn't being used. I ran 3 virus scans from avast, malwarebytes and adwcleaner--nothing showed up. From what i've read online, it's something about cables or scsi or IRQ issues, but i dont know much about computers, so i have no idea what they're talking about. I haven't downloaded anything new in 6months and i've had this issue for about a week. As long as i use this computer, it never happens, only when it's not being used does it happen. HELP!