Test the monitor and cable on a different pc.
Verify they both function.
On cold boot the keyboard and mouse light up. The monitor shows there is no signal. 5-15 minutes later the monitor will turn on and the login screen is visible. It then works fine. There is no problem when restarting the desktop.
I cleaned all apps from startup, all drivers are the latest, ran scandsk for problems. Since the screen opens up on the login screen I can't open in safe mode.
Desktop is a Gateway DX4860- UB32P/ i3 2120 3.3 GHz
Thanks in advance.