What should you do if the computer turns on but shows no display?

If the fans spin and the lights come on but nothing appears on screen, the fault usually lies in the video signal path: RAM seating, the dedicated graphics card connection or the display output circuits on the motherboard. The checks below will narrow it down considerably.

Check these first

• Monitor and cable: Make sure the monitor is on the correct input (HDMI/DisplayPort) and the cable is firmly connected. If possible, try another cable or another monitor.
• Correct output: On a desktop with a dedicated graphics card, plug the cable into the graphics card's output, not the motherboard's.
• External display on a laptop: If the laptop screen is dark, connect an external monitor. If the picture appears there, the problem is most likely the panel, display cable or backlight.
• Beeps and lights: If you hear beeps or see a blinking light at start-up, note the count; many motherboards report RAM or graphics errors this way.

Common causes

• RAM: A loose or faulty memory module stops the device from completing its power-on self-test; the fans spin but no picture appears.
• Graphics card: A problem with the card's power connection, the card itself or its VRAM causes loss of display. See how to tell if a graphics card is faulty.
• Motherboard display output circuit: On devices using integrated graphics, a fault in the motherboard's display output circuits or the CPU power rail cuts the picture.
• BIOS: After an interrupted update the device can hang during start-up; see when BIOS programming is needed.

How we diagnose it

We don't recommend replacing parts without component-level measurement. We measure the power rails and signal paths with an oscilloscope and multimeter and, where needed, locate the abnormally hot area with a thermal camera. That way the source of the fault is found directly instead of by trial and error ("let's swap the RAM, and if that fails, the graphics card").

If the fault is on the graphics card it is handled under GPU and graphics card repair; if it is on the motherboard, under motherboard repair. You can create a repair request for your device, or send it by courier if you are outside Istanbul.