Gpu reaching over 100°C while gaming

[SSoCMBS]

Hey, I built my own PC about 5 months ago and havent been having any problems with it until recently. Now while playing games (Fallout 4, Euro Truck Sim 2) the computer will reboot without warning, at first I suspected the CPU but checking the BIOS straight after reboot temps read at about 50°C. Monitoring the GPU temp during Fallout 4, It rose as far as 102°C before I shutdown Fallout out of fear for the GPU. I believe that the GPU overheating is the problem only I dont understand how this arose as the problem only started occuring 2-3 days ago and I could run these games fine before hand. I have tried the following methods to fix the problem:

1. Moved the Card to a different PCI slot allowing more space for airflow
2. Played with the fans set to a higher RPM
3. Did a clean install of NVIDIA Drivers for GPU
4. I haven't cleaned the case, but it looks fine (Relatively new to computers so I'm not sure if this is stupid or not

The cooling methods helped although they didn't fix the problem, only prolonged the reboot

My Rig:

CPU - Intel I5 4690K
PSU - Corsair CX750M
GPU - MSI GTX 970
MoBo - Gigabyte Z97X Gaming 3
RAM - 8Gb (4x2) Corsair Vengeance
Case - Corsair Carbide Series 200R Windowed Compact ATX

Any help is appreciated!

 

[Robert Cook]

could be a loose or jarred heat sink on GPU.
what is up with the fans on the card, they are spinning and if so at what speed?

 

[SSoCMBS]

could be a loose or jarred heat sink on GPU.
what is up with the fans on the card, they are spinning and if so at what speed?

Well after further investigation it is not my GPU and it is in fact my CPU that is over heating. I used MSI Afterburner to monitor temps and GPU remained around normal however CPU reached afore mentioned very high temps, I'm using a stock heatsink for it but I still dont understand why the sudden huge temperatures

 

[Robert Cook]

did it get bumped when you put in the GPU? also how is airflow, that big card pouts out a fair amount of heat.

 

[The_Tester]

Any BIOS/UEFI tweaks lately? Are you overclocking? Stock intel heatsink or aftermarket solution? My initial thoughts would be to have the case open (insides viewable) and double check to make sure that fans are turning like Robert Cook alluded to. This will also help rule out case heat. Unless you have specifically modified fan speed to be 0 all fans in your setup should be spinning at some speed.

Might not hurt to reapply the thermal compound on the cooling solution/CPU if BIOS/UEFI settings, fans speeds and properly working/installed cooling solutions are taken out of the picture.

 

[Robert Cook]

I think the heat sink is loose, those stock heat sinks are easy to put on wrong.