"no signal"it shows on a scren.

I'm assuming that it worked at one time. If so, then most likely the monitor's signal cable is loose on either the monitor end or on the computer end. Try wiggling the connection and tighten the screws on the connector.

Good luck,
WallyH

It's either the video card or the cable, replace the cable first if that doesn't work then replace the video card

Your motherboard has a white 4 pin port right behind the mouse/keyboard ports. Your PSU needs to be plugged into that port. That supplies power to your CPU socket. Without it, you will get those exact symptoms.