A stress test won't always tell you about every overheated part. So, remove the case cover and use compressed air to blow out all dust from around the processor, heatsink, power supply, and all fans and vents. Make sure all fans are functioning. Run the computer with the case cover off to see if that fixes the issue. If so, it's a heat problem.
Also check the motherboard for swollen or leaking capacitors. The symptoms you described are frequently caused by bad caps. And finally, try replacing the thermal paste on the heatsink.
And as a last test, here, we replace the power supply as they can occasionally be wonky for no reason.
Hope this helps.
Grif
I had the computer system for under 1 year and all of a sudden it started switching off randomly (no bluescreen) when playing games. After the first crash it will start to randomly restart without playing games. First thought was that i have a heat issue but after some stress test the computer passed and did not switch off. There are other times that the pc keeps working fine while playing games.
The games i play are Assassin's Creed, Overwatch, GTA V, FIFA, COD, Battlefield & CSS.
Tests Done:
-Upgraded Bios
-Changed all Drives to new updated
-Changed all Drives to cd drivers when bought
-Tests on FurMark
-Tests on BurnInTest
-Tests on IntelBurnTest
-Tests on Prime95
-Tests on OCCTPT
The Rig is as follows:
Mainboard: ASUS Z97-k
GPU: EVGA 4GB OC GTX970
CPU: Core I5-4690K (3.5GHZ)
RAM: 2x Corsair (CMZ8GX3M1A1600C10)
HDD: 500GB Samung SSD
PSU: V850W CoolerMaster
OS: Windows 8.1 Pro
Temperature Idle:
CPU: 35C Deg
GPU: 36C Deg
Mainboard: 26C Deg
HDD: 35C Deg
Average Temperature while in game (ultra settings)/ Tests:
CPU: 45C Deg
GPU: 75C Deg
Mainboard: 32C Deg
HDD: 35C Deg[
how can i solve this issue or do further test to figure out the solution?
Thanks in advanced.

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