Random shutdowns

[FL630]

Hello,

This has been going on for a while. I randomly get shutdowns from my computer, as if someone has turned it off by the wall. Everything goes black, hear the click of a few relays in the PSU, my LEDs switch off and am left with a dead PC.

Give it a minute or so sometimes it'll switch back on again, sometimes I have to wait 10 minutes before I can turn it on again by myself. From what I can tell there is zero pattern to what's going on with it.

My computer is a i7-4790k, Gigabyte Z97N-Gaming 5 ITX MoBo, Strix GTX 980, EVGA Supernova 750W G2 all water cooled with a 240mm and 280mm radiator, Vadar fans and EKWB blocks. It runs very cool even under load. At this time the CPU is not overclocked and hasn't been since I've been having these problems. The GPU is fairly heavily overclocked but runs very stably with no artifacting or the usual signs of instability.

So, with no rhyme nor reason for the shutdowns... where do I start?

Thanks

 

[FL630]

Thanks chaps. No second PSU sadly and the shutdowns happen so randomly and rarely I could be waiting for another week for it to happen again.

I'll take all the wiring out, tighten or untighten any wrongly tightened screws and see how it goes, plus next time it happens I'll watch the event viewer.

RAM and CPU at stock clocks, I've just taken the OC off my 980.

Thanks all, hopefully it's just something stupid like a loose wire.