[SOLVED] GTX 970 clock speed dropping under load

[Kupp1]

I have a problem with my Asus GTX 970 strix that I bought used yesterday. When idle the clock speed is at the max boost clock of 1253MHz. Whenever I start a game or a stress test the clock speed drops to ~600MHz. If I increase the power target in Asus GPU Tweak II, it stays at ~800MHz. I changed the thermal paste and under load my temps don't go above 42
Also, when I try to play Skyrim, after only about 2 minutes both of my monitors go black and I get earraped because the sounds completely <Mod Edit> up too. Then I have no option but to just hold down the powert button until the pc shuts off.
The previous owner had none of these problems. Yes, I can trust him and he has tried to help me solve these issues.

Things I have tried:
-Deleting the display drivers (including PhysX) using DDU and installing the latest game ready driver.
-Setting the power management mode in nvidia control panel to prefer maximum performance.
-Using the debug mode in nvidia control panel.
-Making sure all the cables are connected.

My system specs:
Intel I5 9400F
Asus prime h310 motherboard
16Gb 3200MHz DDR4
Corsair RM650 PSU
Asus GTX 970 Strix

Any help would be appreciated.

 

[cin19]

Recommend to return it. The GPU has problem.

 

[ninad4c]

I have the same gpu with the same problem, only increasing power target to 120% thing can perform close to a 960.

So far i haven't found any fixes for that but my guess is that it would be something related to either physical damage (it's like some power rail got busted and it's trying to compensate with the remaining ones) or a bad vbios

If you find anything new please let me know.