There is no image, what is from the video card, what is from the VGA motherboard, any thoughts?

Question

Iron

They brought a PC with a problem, there is no image either from the motherboard (VGA) or from a discrete video card. Where to dig?
They advised me to reset the BIOS - I made
the video card 100% working, but the motherboard - I'm not sure.
And the PC starts and all the coolers are spinning.
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I went over and cleaned the RAM with an eraser and it worked: D, thank you all.

Answer 1

- check the power supply;
- pull out everything from the motherboard, except for the processor, connect the speaker, turn it on, listen to the beeps, if it beeps, plug in the memory, turn it on, listen ... plug in the keyboard, look at the diodes at the time of switching on, should blink all three if the computer starts up.