I can't diagnose my system crashes

[JamesOfEarth]

Like many others, I have a pc that is strangely crashing. However, I can't seem to find a problem that matches mine. My pc is completely crashing when I try to tax my system in the slightest. It hasn't started until the last few months. Some games like GTA 5 won't even load before crashing, others, like Total War Warhammer will crash as soon as the campaign map loads. Older games such as Star Wars Rebellion, or Worms Armageddon work perfectly. Two different programs have shown that my pc is running fairly cool, so I'm not suspecting overheating. I replaced my GPU with my wife's and it still crashes. My RAM isn't even close to filling up when I get crashes either. I tried two different PSU's as well, one was only a few days old. I tried using multiple pcie ports for my GPU. I still have about 100 gb available on both of my HD's, and my rig is not overclocked. Any ideas?

Specs:
MOTHERBOARD: M5a99x evo r 2.0
CPU: Amd Fx8350
GPU: Amd Radeon r9 280x
PSU: 700w
MEM: 12 GB DDR3
HDD: 2x 500 GB
OS: Windows 10

 

[badboyrog2]

put somes spec please ... like brand/model
which psu? do you have an aftermarket cpu cooler?
you can not know the real temp on cpu fx series , so be carefull

 

[JamesOfEarth]

My PSU is a Thermaltake tr2 700w 80 plus gold
I am using the stock fan and heatsink. When it does crash, I can touch the heatsink with my bare fingers without any discomfort. My HD's are both Toshiba mk5055gf, my RAM IS 3x4GB Corsair Vengeance 2400mhz sticks
My PC doesn't have one brand in particular, I built it myself.

 

[badboyrog2]

with a fx 8350 you really need a good aftermarket cpu cooler ...get cryorig H5 universal
you need a good mobo with heatsink over the
vrm
wich mobo brand? its impossible to a motherboard do not have a model number

 

[JamesOfEarth]

The motherboard is an Asus M5a99x EVO R2.0 I ordered the cooler you suggested and it should be here tomorrow.

 

[badboyrog2]

``MEM: 12 GB DDR3`` how many ram stick you have?
``Asus M5a99x EVO R2.0`` good motherboard
are you sure your psu work well? can you try with a psu from a friend or??