If you disconnect the power cable it works?
Which power cable you are talking about? Is it the 6pin connector for gpu?
Try using a different pcie slot, if that doesnot works try reverting back to an older bios version. If that works use it if it doesnot repudiate it.
The Power cable is of the Pc...now it's sufficient to switch off the power switch in tha back of the pc.
It's very strange!
If i restart the pc or switch off from Windows ..then the pc in the next start is blocked.
But if i disconnect the power cable or turn off the power switch, it works.
Also if sometimes , after a few minutes, the pc stops.