I'm having an odd PC issue and I wanted to post about it to rule out GPU issues. My hunch is 1) bad wiring in my apartment, 2) bad PSU, or 3) unstable CPU. My PC specs are in my sig. The other pertinent info is I've been running an OC on my GPU's at 1250mhz / stock bios without issue until now. Using the latest nvidia non-beta drivers. About 2 months ago I moved into a new high rise apartment, built in mid-late 80's, in a big city. Since I've moved my lamp really flickers when I play games. It flickered at my old apartment (also built in 80's) but I never had any problems other than the occasional F1 2013 freeze which I thought was normal before given the developers' history. Lamp is plugged into the wall w/out surge protector. My PC is plugged into a surge protector that is plugged into the same outlet as my lamp.
 
When playing F1 2013 I've not been getting stutters, but I've been getting freezes and system reboots. I get the blue screen error message box after reboot. With AC3 and now AC4 the games freeze but system does not reboot. The game applications stop responding. Event viewer shows no major errors (aside from my printer driver, because it is turned off). I've never gotten any GPU driver failure or "GPU driver has stopped responding" messages. I paid close attention just now with AC4, only using 1 GPU at stock settings, and the game stutters badly at the same time my light flickers badly, I didn't crash though (only tried playing for 6-7 mins)
 
Before I reset my CPU to stock, does this sound like a bad building wiring issue / can I assume this is not GPU related? Never would've thought that my PC could destroy games and apartment buildings

I agree with the General, the power supply you have is great, not too aggressive of an overclock on your cpu, sounds like it might be a building issue with you sucking that much juice haha. On a side note, have you tried running system stress tests/bench marking programs?

Thanks for the replies I appreciate it. I placed the lamp on another outlet so now its just the PC and that's it. No lamp flickering at other outlet. I also updated my motherboard bios and have a light OC on the CPU now, 4.4ghz at 1.27v. Ran small FFP within Prime95 for an hour and all was well. I am holding out hope that my CPU OC was not as stable before as I'd thought it was, and that the flickering is just normal.  My laser printer causes the light to flicker too. I played AC4 last night for about an hour and stuttering was still there but no crashes.
 
I did previously run 3dmark11 many times and there was flickering, but nothing crashed. Precision showed voltage staying steady to both GPUs. My scores were as high as everyone else's.
 
Rich- yeah I did some basic Googling on UPS, and I read reports of them frying people's PC's. I will keep researching though, either Cyberpower or APC I think are supposedly decent brands. I don't want to kill my PC.