PC Restarting Playing Games

[MortalBumFat]

I've had my Pc for around a year and a half now and in the last couple of months its started to restart when playing games like "rocket League" "spec ops: the line" and others. All these games i should be able to play at high settings but I've had to drop down to medium or low to try and stop it from restarting (never restarts when i'm just doing idle stuff). I've been measuring my temps for my GPU and CPU and they are all under the dangerous temps when looking at the manufactures websites. I'm trying to figure out if its my PSU not being able supply enough power or if i've got a faulty GPU (which i really don't want). If anybody might have any clues on trying to figure out the problem is or have solved it i would really appreciate it
Specs:
Processor (CPU) AMD FX-8320 Eight Core CPU (3.50GHz/8MB CACHE/AM3+)
Motherboard ASUS® M5A97 LE R2.0 (DDR3, USB3.0, 6Gb/s)
Memory (RAM) 8GB KINGSTON DUAL-DDR3 1600MHz (1 x 8GB)
Graphics Card 2GB NVIDIA GEFORCE GTX 660 - 2 x DVI, HDMI, - 3D Vision Ready
1st Hard Disk 1TB 3.5" SATA-III 6GB/s HDD 7200RPM 32MB CACHE

 

[mantadog]

What temps did you record? Its possible they spike and cause a thermal shutdown but are showing normal when you view. what temps did you get at what loads?

Otherwise I think you could be right with the 2 other possibilities, PSU could be on its way out or just a flat out faulty component. Could be a tricky one to figure out by the sounds of it, are you comfortable playing about inside the chassis?

 

[MortalBumFat]

Well from what I recall I'm normally getting around 50-60 degrees (maybe some 70 spikes) on my GPU when its around 90% usage. CPU never really gets hotter then 50 when looking at "core temp" but normally my games are windowed when looking at that. I've been playing rocket league in power saving mode which has stopped it from crashing but that pretty much destroys my frame rate in any other game I try to use it. I've done virus checks as well so don't think it will down to that either. Do you know of any decent stress test programmes to test my components?
I'm not the most confident when playing around with my hardware but i can have a go.

thanks