A new one but still the same problem

Registration date
Friday October 11, 2019
Last seen
October 11, 2019
Hi all,
since a few days now my pc won’t boot up as it usually did. Every time i turn it on my screen shows no “No Video Input” and my keyboard and mouse LED’s also won’t work.
The fans inside my PC are running though.

I tried changing the PSU with a new one but still the same problem.

Here’s what’s weird : When i put in my old GTX 750 my PC does indeed start as it should but after a 2-3 minutes after logging into windows 10 the PC automatically restarts over and over.

Where could be the problem?
If my graphics card is the problem, why does my old gtx 750 makes my pc run but restart over and over again?

Am i missing out on something?