You turn on your PC and the monitor says "No Signal" — or "Check Cable" — or just goes black with the power light blinking. The PC sounds like it's running, but you have no display. This is a frustrating experience, especially because the cause could be anything from a simple loose cable to a dead graphics card.
The key is to work through this systematically, starting with the simplest possible causes and moving toward the more complex ones. Don't jump to conclusions — "No Signal" is often caused by the simplest things.
Step 1: Check the Obvious Stuff First
You'd be surprised how often these basic checks solve the problem:
- Is the monitor actually on? Check the power indicator light on the monitor. Make sure the monitor's power cable is plugged in and the power switch (if there is one) is on.
- Is the monitor on the correct input? Monitors have an input selector (usually a button or menu on the monitor itself). If you have HDMI-1, HDMI-2, and DisplayPort options and the cable is in HDMI-2 but the monitor is set to HDMI-1, you'll see No Signal. Cycle through inputs using the monitor's buttons.
- Is the cable fully seated? HDMI and DisplayPort cables can feel plugged in but actually be slightly loose. Unplug the cable from both the PC and the monitor and firmly reinsert it.
Step 2: Try a Different Cable
HDMI cables fail more often than people expect. If you have another HDMI cable, try it. If the signal appears, the original cable was the problem. Also try a DisplayPort cable if your monitor and GPU support it — DisplayPort is generally more reliable for high-refresh-rate setups.
Step 3: Verify Where You're Plugging In
This is one of the most common mistakes. Many desktop PCs have two sets of video outputs:
- GPU outputs: On the graphics card itself, lower on the back of the PC case
- Motherboard outputs: Higher up on the back of the case, near the USB ports and audio jacks
If you have a dedicated GPU, you must plug into the GPU outputs. Plugging into the motherboard outputs when a GPU is installed will give you No Signal in most configurations, because the dedicated GPU takes over the display function.
Conversely, if you have no dedicated GPU and are using the CPU's integrated graphics, plug into the motherboard outputs, not where you'd expect a GPU to be.
Step 4: Reseat the GPU
The GPU sits in a PCIe slot on the motherboard. Vibration, thermal expansion, and everyday use can cause it to work slightly loose over time. Power down completely, open the case, press the small release latch at the end of the PCIe slot, and remove the GPU. Reinsert it firmly until you hear the latch click. Also check that the GPU's power connectors (6-pin or 8-pin cables from the PSU) are fully seated.
Step 5: Test With Integrated Graphics
If you have a CPU with integrated graphics (most Intel CPUs have this, some AMD Ryzen CPUs do too), temporarily remove the dedicated GPU and plug the monitor into the motherboard's video output. If you get a signal this way, the dedicated GPU is the problem. If you get no signal even from integrated graphics, the issue is elsewhere — possibly the monitor, motherboard, or a BIOS setting.
Step 6: Try a Different Monitor or TV
If possible, plug your PC into a different screen — even a TV with an HDMI port. If you get an image on the TV but not the monitor, the monitor itself is the problem. Monitors can fail — particularly the internal power circuitry and the backlight.
Step 7: Check BIOS Settings (Advanced)
Some BIOS configurations prioritise one video output type over another. If you recently changed BIOS settings or the CMOS battery died, default settings may have changed. Unfortunately, if you have no display at all, you can't easily access BIOS. Try resetting the BIOS by removing the CMOS battery for 30 seconds or using the clear CMOS jumper on the motherboard (check your motherboard manual for its location).
Common Nigeria-Specific Causes
In Nigeria, the additional culprits are:
- Power surge killed the GPU: After a power event, the GPU is one of the first casualties. A dead GPU will show no signal. Check if the GPU fans spin when the PC is on — if they don't spin at all under load, the GPU may have failed.
- Monitor damaged by surge: Monitors are also vulnerable to surges, especially through HDMI cables (surges can travel through cables). If your monitor was not on a UPS during a surge event, test it with another device.
When It's Beyond DIY
If you've tried everything above and still have no signal, you're likely dealing with a failed GPU, a failed monitor, or a more fundamental motherboard issue. A technician can test each component individually with known-good replacements to isolate the failure.