Pc sudden crash when playing game only!

[Alexander 123]

So, I got a gigabyte gtx 660 oc from ebay (im on a tight budget) to pair with my i3 2100 both running on stock speeds they both ran fine on my thermaltake smart m650w psu for about 2 days for 6-12h until today, after 9 hours of gaming ( i know...)
My pc crashed out of nowhere with no blue/black screen and it automatically restarted, i was playing fallout 4 then i updated my drivers and tried gta v, same thing but it crashed after moments only.
i suspect its the power supply though it hasnt been making any noise its been sitting for a along time( it was there before i got anything else) i opened but it was completely clean no dust whatsoever i did a full scan and nothing was found.
Note: the pc will run fine if i dont play games i tried synthetic gpu benchmarks and they run fine and the pc wont crash unless im playing a heavily demanding game.
Is it software? did my psu die? Is it my graphics card?
Please help!!!

 

[Bart ix 123]

Full specs of PC please

 

[Zerk2012]

download OCCT and run that to stress the CPU and run your video card benchmark program at the same time that will simulate your gaming load.
Keep a eye on your temps but I would say the power supply.

 

[Alexander 123]

Alright so the specs are:
I3 2100 that i know isnt the problem
Gigabyte gtx 660 oc i supect
Asrock h61m-dgs
Thermaltake smart m650w i suspect
8gb ram from team elite that i know are not the problem
A 60 gb ssd from kingston and a 500gb hdd ftom WD
Yesterday i ran furmark for about 3 minutes and thatvwas enough to crash it the temps are no problem never getting hotter that 60°c on the gpu and 50°c on the cpu.
Today ill ask my friend if i can try my gpu in his rig.
And thanks for the quick reply!

 

[Revound]

If thermals are okay, first thing I would look at is the power supply.

 

[Alexander 123]

Alright so i couldnt try my gpu at my friends rig ifigured even if the gpu is dead i would like to get a psu anyway beacuse this on eseems very sketchy i mean thers not even an official page for it.
So i will first get a psu and report back thanks for all the support guys!

 

[Revound]

Alright so i couldnt try my gpu at my friends rig ifigured even if the gpu is dead i would like to get a psu anyway beacuse this on eseems very sketchy i mean thers not even an official page for it.
So i will first get a psu and report back thanks for all the support guys!

Take a quick look at our tier list: http://www.tomshardware.co.uk/forum/id-2547993/psu-tier-list.html

Try to get at least a tier 3, preferably Tier 1/Tier 2 if budget allows.

Never go cheap on a power supply.

Hope this sorts out your problem.

EDIT: By the looks of it your PSU is listed as tier 4 on the list. Would definitely upgrade anyways. "Built down to a low price. Not exactly the most stable units ever created. Very basic safety circuitry or even thin gauge wiring used. Not for gaming rigs or overclocking systems of any kind. Avoid unless your budget dictates your choice."

 

[Alexander 123]

Yeah guys the new psu made everytging work again fine
Its a be quiet 500w efficient power psu that i got off of ebay.
Thank you so much for the support!