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As per your first comments :- but the thing is this same motherboard ran this 970 for 4 years with no issue and never shut down and even the power supply is of best quality of Seasonic because this same motherboard ran my 970 for 4 years at temps of 65-70c with no issues at all
As you are told me that you are using motherboard and same graphic card with all same parts from last 4 years and it was working fine means not shutting down at a temprature of 65C to 70C and graphics card.
But previously commented "I have tried putting a new GTX 1050ti in my computer and I am still having the same problem." so i told you that may be motherboard have problem but there may be other problems factors reasons for shutting down also may be driver software or other parts heatings
then as per idea my thoughts either your GPU or CPU or RAM or chips somewhere in motherboard or Graphic card or some thing is overheating by time or dust or carbon in parts...you should check or compare temperature through softwares listed below of all components (CPU RAM CHIPS GPU) previously and now and find which part is more heating now it may be shutting down due to GPU throttle limit or may be due to heat of some other parts
The game you playing or any other software or any other Memory resident program (antivirus or any softwares) or any software to may be CONFLICTING restarting or shutting down the PC you should cross check system files malwares softwares AND CONFLICTS.
Sometime system shutdown is due to HDD reading errors on particular sectors so u should scan defrag HDD and chkdsk also
try to find new update GPU drivers or motherboard BIOs updates or GPU chips Updates any other update for chipset drivers updated may be they are corrupted or giving some problems
Try to change Game lower down or GPU settings of Frame rate or resolutions or CPU RAM usage or any other system setting which may solve your problems
As per your second comments :- try the increasing temp limit for my gpu because I think that can solve the issue, but unfortunately my motherboard has no options to increase temp limit of gpu to avoid it from shutting down. Do you know of any software which I can use to increase temp limit of gpu?
Now my views:-
I know you are using graphic card GPU GTX 970 chipset but you did not mentioned and told of which Company (MSI ASUS NVedia) or any other company of your graphics card. Kindly mention in question company of your devices then it will be easier to find and troubleshoot your problem .
Find Default GPU The throttle temperature limit set of card of your specific Manufacturing company.
As per my suggestions GPU throttle temperature limit is set to protect you GPU motherboard and CPU from being Damaged by overheating or burning its not advisable to increase those limits its better to make your GPU CPU cool by Fans Heat Sinks or increasing fan speeds or purchasing new big cabinet fans or CPU or GPU fans or water coiling. Still you can carefully try to increase the throttle limit by software but try to keep it low by Default and preferred throttle limit of the company
I am below sharing below links of software's by various company without proper knowing about your Graphic car company and mother board company. Its advisable only use or You should try with the software of the manufacturing dont try 3rd party or softwares of other companies with your card they may force but may damage your card
According to Nvdeia website link says:-
NVIDIA GPUs are designed to operate reliably up to their maximum specified operating temperature. This maximum temperature varies by GPU. Refer to the nvidia.com product page for individual GPU specifications. If a GPU hits the maximum temperature, the driver will throttle down performance to attempt to bring temperature back underneath the maximum specification. If the GPU temperature continues to increase despite the performance throttling, the GPU will shutdown the system to prevent damage to the graphics card. Performance utilities such as EVGA Precision or GPU-Z can be used to monitor temperature of NVIDIA GPUs. If a GPU is hitting the maximum temperature, improved system cooling via an added system fan in the PC can help to reduce temperatures.
3rd party Overclocking tools (not ADVISABLE)
if you overclock then be sure to have WATER COOLING AND COOLERS OF FOR YOUR CPU GPUS RAMS
EVGA Precision X1.
Introducing EVGA Precision X1. With a brand new layout, completely new codebase, new features and more, the new EVGA Precision X1 software is faster, easier and better than ever. When paired with an NVIDIA Turing graphics card, the new EVGA Precision X1 will unleash its full potential with a built in overclock scanner, adjustable frequency curve and RGB LED control.
The world’s most recognized and widely used graphics card overclocking utility which gives you full control of your graphics cards. It provides an incredibly detailed overview of your hardware and comes with some additional features such as customizing fan profiles, benchmarking and video recording. MSI Afterburner is available completely free of charge and can be used with graphics cards from all brands.
Download ASUS GPUTweak II
ASUS GPU Tweak II provides an intuitive interface to access serious functionalities, all right at your fingertips. And the best part is, you can access all that on-the-fly, even in-game ─ all with one click.
Enjoy your music and videos by clicking Silent Mode
Game for hours on with Gaming Mode as the default setting in ASUS graphics cards
Bench and play the most demanding games by clicking OC Mode to unlock maximum performance
Stream and record your gameplay on-the-fly with XSplit Gamecaster
Capture and share videos, screenshots, and livestreams with friends. Keep your drivers up to date and optimize your game settings. GeForce Experience™ lets you do it all, making it the super essential companion to your GeForce® graphics card.
OPTIMIZE YOUR GAME SETTINGS
GeForce Experience takes the hassle out of PC gaming by configuring your game’s graphics settings for you. Don’t know what texture filtering level to set in Overwatch? Not to worry. NVIDIA taps into the power of the NVIDIA cloud data center to test thousands of PC hardware configurations and find the best balance of performance and image quality. Then it automatically configures personalized graphics settings based on your PC’s GPU, CPU, and display.
NVIDIA Inspector is a utility to read all GPU relevant data from the NVIDIA driver. ... Also included is monitoring of GPU parameters like clocks, temperature and fan speed. Multi Display Power Saver lets you reduce power consumption of the NVIDIA card by picking a lower power-state for multi-display
NVIDIA Inspector is a utility to read all GPU relevant data from the NVIDIA driver. It also supports overclocking and changing driver settings, for example to enable SLI for unsupported games.
Also included is monitoring of GPU parameters like clocks, temperature and fan speed.
Multi Display Power Saver lets you reduce power consumption of the NVIDIA card by picking a lower power-state for multi-display configurations.
if any of my answer works and suits your problem then do tell me in comments for my knowledge and research which one worked for you and if not then feel free to ask further clarification queries regarding the answer in comments . If worked then dont forget to vote for my answers and accept the answer.