Random reboots while playing games

[saatlol]

So since a few months my computer randomly reboots while playing games. This happens almost instantly when I run games like RuneScape or League of Legends. However the weird thing is, when I play RuneScape with their legacy client which runs Java it has no issues while playing.. No reboots or anything.

Windows' logs show a kernel issue but no specifics. I tried cleaning the dust, change GPU slot.. Made no difference. Haven't overclocked my rig.

It sounds like a PSU issue but I have no spare PSU laying around.

System specs:
i7 4790k
Cooler Master GM G750M
Asus STRIX GTX 970
8GB Corsair Vengeance RAM.
Cooler Master Nepton 240M watercooling

I am really desperate at this point. Can anyone help me?

 

[saatlol]

Anyone?

 

[osisteve]

Download and run RealTemp. Configure it so it writes to a log file every 5 seconds. Then use your computer as normal, and run some games. After the reboot check the RealTemp long file for any spikes in temperature. If the temp is a lot higher, your reboot issue may be related to overheating. I see you already have a bunch of cooling options, but you never know if something is out of whack. CPU thermal paste having dislodged could also be another one.