Computer randomly shuts off and wont turn back on for few minutes.

Hello,

I recently built my first gaming rig. And up until now, it has done very well:

- Asus P8Z77-V Deluxe
- Intel i7 3770K (not OC, but TPU switch on, and that's all I've done)
- Corsair H100 Cooling System
- Corsair Dominator GT 4x4gb 2133mhz DDR3
- EVGA GTX 580 Classified
- Corsair 1050W PSU

Built it two weeks ago. Never had any problems. Few days ago, I switched TPU to "ON" and clocks 4.2ghz under load, temps don't really go over 50s, high 20s at idle.

But now every once in a while (several hours of gaming), it will randomly shut off and the power button will not turn it on. All other components plugged in (monitor, speakers) are still on; motherboard LEDs which turn on when connected to power (even when the PC is off) are also still on. But I have to let it sit for a few minutes, turn off the PSU and unplug it before it finally turns back on.

Given that I'm new I have no idea how to troubleshoot, but my ideas:
- is just flipping the ASUS mobo TPU switch ON without any other adjustments unstable? Is TPU ON in general unstable?
- is my PSU broken? (Seemed fine before and will give several hours of power fine, plus Corsair seems well made)
- surge suppressor never shorted or w/e, but is this a fluctuation voltage in the house issue? Seems strange that it would then not immediately turn on, if this was the case.
- Is this indicative of some other hardware or software malfunction?

I'll turn the TPU off for now, but given this only happens every-so-often (i've accidently left the CPU on over night and it's still on in the morning, but it randomly shut off while ilde before), i'm not sure whether this more of a general issue rather than just now that i turned TPU on.

THX for the help!