Graphics card turns off without overheating?

As already mentioned in the title, my graphics card simply shuts off as soon as I play no matter which game

CPU: Intel Core i7 4790k (not overclocked)

GPU: Asus Strix gtx 980 (not overclocked)

Ram: 32 GB Kingston ddr3 ram 800mhz

Mboard: Gigabyte h97-hd3

Power Supply: Cougar HEC- 550 TE (550 Watt 80plus Bronze)

I've started to test, speccy and minecraft to see how far the gpu heats up before it just shuts off.

It turns off at 52 degrees and that's not normal.

I do not get any graphic errors and the sound continues to run shortly after switching off.

I play in full HD (1080p) 1680 x 1050

With only one screen and no other programs in the background

I have only had this problem for 2 days, but I did not download or install anything before that, which is why I exclude it from Windows.

However, I have no idea what to do

First of all, 1680 x 1050 is not Full HD, because Full HD is 1920 x 1080 …

and second, take HWinfo64 for your temperate check…

Any updates of Windows or your graphics card, can lead to such errors already…

Spontaneously I would tap on a problem with the power supply, but for sure you can't say that. Your Cougar (HEC) is six years old and actually of reasonable quality, which of course does not exclude it as a source of error.
Try it out if the PC crashes with a CPU benchmark (like Prime95). If so are power supply or (unlikely) motherboard blame, if not you are not smarter than before.
Did you update the video driver to the latest release version, and try an older version?
Did you check the CPU temperature?

If all of this does not help - do you have 60 euro to buy a new power supply on suspicion?

Msi Afterburner and GPU-Z show the same temperature as speccy so I conclude that the gpu shuts off due to high temperature

Then you have a driver problem…

I also had, when ARK just closed by itself, without reporting a mistake…

Uninstall Grakatreiber and install previous version… The 436.xxx is not running very well…

Before you swap hardware, you should first check the drivers… Is cheaper and works better

Have already checked with the drivers and it is not because had the problem with the driver before the update, after the update and after the reset of the driver

Whether it works depends on whether the drivers are the problem. Possible, but of course I have written that too.
Of course, what you should also try are different applications. It could also be the game.

That is true…

On the drivers it is not, the CPU has only 65 degrees in the stress test and the PC does not turn off

When I play this only the gpu does what I can't understand at a temperature of 52

Yes, then I would strongly suspect the power supply. Do you have another similar power-hungry graphics card to try this out?

No, unfortunately not

Okay, then, if you have software problems out of the question, it's just a matter of renewing hardware on suspicion. And as I said, it is probably the power supply, in addition, the motherboard would be possible, as well as hard disk or RAM - but that's unlikely.
If you want to try a new power supply, buy a be quiet! Pure Power 11 500W for 60 euro, that's a good compromise between quality, volume and price.
Otherwise, at least I would not think about the problem.