Complete computer lockup

[TheMakaan 12]

I've been having this problem for about a week, now I thought it was my GFX card,(980GTX) but I just borrowed a spare card (590GTX) and the same issue still occurs,I will be playing normaly everything fine and it would just lock up on me, it seems to not have a specific time frame that it happens either 2 hours or 2mins after getting into game play, It seems to just complete lock up my system, and have to power off the system, the reset button once hit takes alittle longer then normal to reboot my system, I've tried new drivers different cards I did a system reformat before thinking it was a bug, did a test on my ram and CPU and GPU seeing if they could be the problem, it seems to be only Arma 3 it happens too, tho I don't really have any other games as resource demanding as Arma 3, 

Also I've deleted the entire Arma 3 game and re downloaded it from scratch and it is still locking up for me.

Hope someone can help my System is as Follows

Win7
16gb Ram
Cpu 3930K
GFX 980GTX

[Jackal326 1158]

Its not an issue I've personally encountered before (with ArmA3 anyway), but it sounds like an overheat issue. I had similar problems with OFP shortly before my GFX died and took the motherboard with it. Have you run any temperature monitoring software with an on-screen overlay whilst playing to see if it spikes and locks you up?

[TheMakaan 12]

I did do a GPUZ Sensor list for my GFX card the hottest it got was 62 degrees,

not sure about my CPU how can I monitor that while in game, thanks for reply too,

any help or speculation would be good.

[jumpinghubert 48]

Hi, to suspend cpu overheating test your pc with prime95 for a while.

[darksteeljorge 10]

I think what you mean and this happened to me, I was certain I had a 500w psu when i actually had a 285psu i bought a new 550psu for 20 bucks or something and no problems other than my arma wont launch since 1.46.  But the new psu fixed it

[pvt. partz 248]

To control and monitor your temps for CPU/GPU use MSI Afterburner