Windows 7: BSOD playing various games, unknown (and seemingly different) reasons

Hi there,
my computer crashes from time to time. As far as I've noticed it only happens when I play games. It isn't any game in particular, but as far as I remember it has happened in the following:
Skyrim
Just Cause 2
Saints Row: The Third
Terraria
Call of Duty: Modern Warfare 3

I've only recently enabled minidumps, so I have at the moment only one minidump to attach. I will upload more when my computer crashes again.

Some additional info:
Sometimes the computer crashes without any BSOD.
The screen often looks strange before the crash. A lot of small lines in different colors, everywhere on the screen. Like if the pixels were 50 px wide.
I have two monitors plugged in and one TV (through HDMI). I don't know if that changes anything, but anyway it can be worth mentioning.
I've run Memtest86+ for seven passes, no errors found.

Attached is the Seven Forums zip, containing info and the minidump.

Thanks in advance!

Welcome
The one minidmp, does not give much information. When you get a few more upload in this thread.