Computer Lock up with looping buzzing noise?

[KhaosNation]

Hi all

Having trouble diagnosing what is going with my rig as there are certain exceptions to when this issue occurs, appreciate any help I can get to figure out what the problem is.

I first had this situation happen to me when the stock heatsink wasn't mounted properly. Since then it was all smooth sailing.

I've moved to another country and keeping my air conditioning on all the time is no longer an option so once in a while, my computer locks up with the buzzing noise for specific reasons or sometimes random.
I first experienced it again when I tried to launch Xcom Enemy Unknown off of Steam. This also happened with Overwatch originally but I've since reinstalled windows which seems to have remedied the situation (for Overwatch at least, haven't run Xcom so far).

Recently experienced this issue again mid game in Overwatch as well as in Star Citizen and the system lock up has so far happened twice just watching videos on youtube which is an indicator to me now that it shouldnt be a thermal issue as I've already re applied some thermal paste replacing the stock stuff with some higher quality noctua paste.

I've attempted a quick 20 min stress test on my CPU (preliminary results are clear as it wasn't exactly a very long stress test, temperatures did not want to go past 84c)
a quick 15 mins memory test completed with that pre installed windows memory tester (Windows Memory Diagnostic). Again so far so good.

I've yet to have time to test out the GPU but I'm lead to believe its still CPU given the news and information about the i7 4790K

Here's my set up:
i7 4790K @ stock clock
EVGA Z97 Classified motherboard
MSI GTX 970
Kingston HyperX 2x4GB @ 1600MHZ





 

[KhaosNation]

probably worth mentioning that I've checked the event logs and the only thing I could that was note worthy were the system unexpectedly shutting down (from me doing the long press on the power button).

I'm still reviewing the logs to see if I catch anything