Windows 7 Pro 64bit Unexpected Crashes

It all started last weekend when I was trying to run Red Faction II, I changed the advanced boot configuration to use 2048 memory because apparently the game will not run otherwise (I did a lot of forum checking to find this solution). I was able to play the game fine, and there were no errors with my computer for a long while. Then I was playing Borderlands and my computer froze (The screen had many broken lines of color from the game and was playing a nonstop sound). After I rebooted the system and logged into my computer to check to see what the error was, it crashed again, only this time it went to the screen where it dumps the physical memory.Since then I was able to get the computer stable enough to use, but have not managed to find the error. I restored the boot settings to normal, and have ran memtest two times, and checked for errors in the hard drive once. Yesterday I tried running Borderlands Two and it crashed in a similar way to when I ran Borderlands, approximately 20-30 minutes after game start. I still have yet to be able to pinpoint the exact error causing these crashes.I checked my system logs and the only critical error I can find is kernal-power, I can paste the details upon request, but this gives no real information other than unexpected shut down.

I have checked other threads but was unable to find a solution, and I am currently unsure if it is a hardware problem or software problem. Initially I thought it was my RAM but tests indicated no errors.note: I have two different brands and sizes of RAM cards, but this has never been an error before, and I have run games extensively on this machine. It has been able to run such games as Skyrim, Borderlands, Minecraft, and various other games on the highest graphical settings with no problems.

System info: I'm pasting all things that I think may be relevant, sorry if it is a lot
OS NameMicrosoft Windows 7 Professional
System ManufacturerMSI
System ModelMS-7673
System Typex64-based PC
ProcessorIntel(R) Core(TM) i5-2500K CPU @ 3.30GHz, 3301 Mhz, 4 Core(s), 4 Logical Processor(s)
BIOS Version/DateAmerican Megatrends Inc. V1.18, 2/22/2012

[code].....