Computer Crashing During Arma 2

[so keaton]

Hey guys so i have had my personal gaming rig that i built for a little over a year now and until recently everything has been going well. Last summer i played a lot of arma 2 dayz mod and i have recently come back to the game in the past few weeks however this time i have encountered a problem. Every time i play dayz it goes well for about 30 minutes but then my computer shuts down randomly and it takes a little while before it automatically turns itself back on. Its so strange to me because my computer has well above the necessary specs to run the game on maxed settings (i5 3570k, gtx 660 ftw, 128gb ssd, 1tb hardrive, msi z77 gaming mobo) and last summer it ran the game just fine for hours and hours on end with no problems. Also before the computer turns off it shows no signs of stuggling and maintains 60fps and doesnt seem to be too hot. Even though i built the computer im not very skilled at troubleshooting and i have no idea how to figure out whats wrong with it. Again it only crashes when i play this game, but i have no other demanding games on my pc to test it with ( i mostly play minecraft and runescape.) Is it a problem with my graphics card? (nvidia gefore drivers are up to date.) Is it a problem with my cpu or mobo? or is it a software problem. I really hope its not too bad because i spent a lot making this rig and its worked fine up until when i try to play this game. If anyone has any solutions please let me  know. 

[Lima123]

ArmA 2 is a very CPU intensive program, ( Play DayZ mod myself) Monitor your CPU Heat and CPU Usage, And GPU to see if thats doing anything 

[Lima123]

Oh as well, because ArmA 2 is a CPU intensive program. Check your thermal compound on your CPU, if there's not much that can cause heat and more power consumption. If there's to much heat. PC TURNS OFF! Heat is a main thing to much and BANG OFF .... IF you want to talk about it more with me add my me on skype :   liam.eary1      We could even play DayZ Mod  

[Lima123]

I like Runescape tooo! AMAZING GAME MAN, ( Minecraft too )