New build powering off randomly?

[stretchedmonkey]

Hey all, I'm having a bit of trouble with my new build. I've recently gone through hell and back with my recent build, I had a problem with it running incredibly slow and buggy so I decided just to do an entire upgrade (i was planning on upgrading this spring before DOOM comes out anyways). I've replaced EVERYTHING besides the Power supply, Hard drive, and RAM. Currently I'm working with a

NZXT S340 Case
Gigabyte 78LMT-USB3 motherboard
AMD FX 8350 8-core 4.0GHz
Radeon R7 370
Corsair H60 liquid cooling
8 gigs of Ballistix? RAM
Corsair CX600 power supply

I had issues with my old build, and the guy at microcenter who ran a diagnostics determined it was most likely a Windows 10 problem, and he got it to post, but also said it was running incredibly slow, and no windows features would work. I upgraded parts anyways, and rebuilt the entire machine, and got it to finally power up and display properly, but the slow problem was indeed still there. I reformatted Windows 10, and everything has been working fine for about a week. HOWEVER. Today, 3 different times, my computer has completely powered off randomly and I cannot figure out why. My temps all seem to be fine, I checked them through Speedfan. I made sure all of my hardware is compatible through PCPartPicker, so that's all good, however I did read that sometimes the AMD 8350 gives fits with certain boards even though it is compatible. I'm wondering if there's an easy remedy to find out what the problem could be? There doesn't seem to be any overheating issues, I've made sure temps are good, I've put my hand by the power supply after it's shut off, no heat. Any ideas?

 

[bignastyid]

2 possible hardware problems just looking at the specs. That motherboards VRMS cant handle a 125w CPU and will usually cause throttling and can cause shutdowns. While on paper the cpu is supported, in practice it tens to not work so well and the addition of a aio cooler will make this worse as the stock cooler will direct air over the vrms to help cool them and the aio directs air away from the vrms making them run even hotter, this is probably why its slow and buggy and the vrms are constantly throttling the cpu(monitor the cpu frequency to confirm). The other is the PSU. Random shutdowns and shutdowns under load are a common issue with the CXs it could be failing secondary capacitors or the otp kicking in and shutting it down if the psu is getting hot.