Screen goes black suddently

So these are the settings i had before and were working fine for 2 weeks now.

https://preview.redd.it/yq2crwksl0d71.png?width=1898&format=png&auto=webp&s=1272cf8ea48526bf738f11af52e71ec0d8289d77

Now the screen goes black if i set the memory clock to 800+.

Any idea what changed or what is causing this?