The PC does not display an image after replacing the thermal paste. What to do?

Question

Computers

The PC stood for 10 years without changing the thermal paste and without any maintenance. It was decided to replace the thermal paste on the processor and video card. The cover was removed, cleaned of dust, the processor cooler was removed, the video card was removed. The Intel processor was carefully inserted into the socket. Vidyakha neatly smeared and inserted back.
After installing all the equipment, the PC starts up. All coolers work. But the image is not output to either HDMI or VGA. The processor works and heats up, the video card also works and also heats up, everything plows. The only assumption is the wires, because as I was told this problem was before. But there is another joke, the keyboard does not work when connected to a PC. That is, if you connect a mouse to any port, it works and glows, but Klava does not.

Honestly, I have no idea what happened.

Answer 1

First you need to check that all power wires are connected to the motherboard and to the video card, if it has a separate power supply. Did not help? It is necessary to turn off the external power and remove the battery, then press the power button to remove the residual charge from the capacitors. After that, insert the battery into place, apply power and try to start. It would be nice if a PC speaker was connected to the motherboard - you can often understand what's going on by its signals.