A lot of things.

Power supply problems can mimic a lot of things. A fairly easy way to see if it is a likely issue is to get something to monitor your voltage rails while under load, a program like OCCT is good for this. You're 12v, 5v and 3.3 v rail shouldn't deviate more than 10% under load. 

It used to also be caused by windows registry and/or driver issues but since windows 7 I haven't had much issues related to that, but as a whole I'm not sure.

It can also be a ram issue, if you have a bad stick, so you can run memtest to see if that's an issue.
It can also be GPU, or motherboard, But, I've had a lot less issues with these. 

Question,

CGI- when you built your computer did you stress test it?

It seems that you aren't overclocking atleast currently based on your 3770k still being at 3.5 ghz correct? You shouldn't have to stress test it because you're using stock speeds.

But, I still like to stress test things when I build for other people as it's a good indicator of stability in the long run. Little issues with say power supply, memory or videocard are brought to the front quickly when it's easier to return or exchange compared to a few months down the road.

yay

have some random XCOM screens

That was exactly the mission I was talking about. But I had much more enemies on screen. Well you had one of the big drones so i guess it wasn't that easier either.

Sectopods are the worst, and I didn't have any HEAT Heavies. The narrow choke plus grenade throwing Elites (I can't belive they actually called them that and made them look so much like the Halo ones lol) on high ground is a bitch as well. One Sectopod can wrek an entire squad with it's double attack with does 12 DMG which was a one shot kill with my low rank squad plus the always active Overwatch (so moving into range can get you killed before you even get close), the only saving grace is that it's mortar hits the roof. 

Anyway time to start my third Iron Man Classic run, good fucking god it is brutal. I hope there is another patch soon because it's pretty buggy at the moment. 

most good mods will come with a readme file with install instructions.

No supersampling? lol I thought you would be into that kind of thing especially as you should have GPU power to burn.

Tribes: Ascend

TERA:

Vindictus:

Boobs, I mean, Dragon Age: