Why does my computer turn on but show nothing on the screen?
Fans spinning, lights on, and a completely black screen. How to tell within a few minutes whether the fault is the display, the graphics output, the memory or the machine itself — and what the beeps and blink codes are telling you.
- Difficulty
- beginner
- Time
- 35 min
- Read
- 6 min
Short answer
Work out whether the machine ever shows anything at all, even for a second. If you never see the manufacturer logo, the machine is failing before it can draw anything, and memory or a display connection is the usual cause. If you see the logo and then it goes black, the machine is starting fine and the fault is in Windows or the graphics driver. Those two answers lead to completely different fixes.
A black screen with the machine apparently running is one of the most alarming faults and one of the most frequently misdiagnosed, because "it is on" and "it is working" are not the same thing. Fans spin on power alone. What matters is whether the machine ever gets far enough to draw the manufacturer logo, because that logo is drawn by the firmware, before Windows exists. Seeing it proves the processor, the memory and the display path all work, which eliminates most of the frightening possibilities at once. Not seeing it means the machine is failing very early, and early failures have a short list of causes.
Step by step
- Watch closely for the logo through one full power-on.Power the machine off completely, then on, and watch the screen from the first second. A manufacturer logo, a spinning dot, a firmware prompt, or any flash of backlight all count. This one observation splits the problem in half and everything below depends on it.
- Confirm the screen is actually being fed something.On a desktop, check the monitor is on the right input, that its own power light is on, and swap the cable and the port. On a laptop, shine a torch at an angle across the screen — if you can faintly see a desktop or a login box, the panel is fine and the backlight has failed, which is a repair rather than a mystery.
- Plug in an external monitor.On a laptop this is the decisive test. A clean picture on an external screen means the computer is fully working and the fault is the built-in panel, its backlight, or the cable through the hinge. Nothing on either screen moves the problem back into the machine.
- Listen and look for a code.Many machines report early failures with beeps, or by blinking the power or caps-lock light in a pattern. The pattern is not decorative — every manufacturer publishes what theirs mean, and the pattern usually names the failed subsystem directly, most often memory. Count the beeps or blinks and look them up for your make and model.
- Reseat the memory.The most common cause of a machine that powers on and never draws anything is a memory module that has crept out of its slot, often after being moved or opened. Powered off and unplugged, take each module out and push it back until both clips click. On a desktop, try one module at a time in the first slot.
- Drain the residual power.Shut down, unplug from the mains, remove the battery if it is removable, and hold the power button for thirty seconds. This clears a stuck power state that can hold a machine in a half-on condition with no display. It is free, harmless and works more often than it has any right to.
- If you get the logo and then black, treat it as a Windows fault.The machine is starting. A black screen with a movable mouse pointer usually means the desktop shell has failed and Ctrl-Alt-Delete will still work. A black screen with no pointer after the logo usually means a graphics driver. Boot into safe mode and roll the display driver back — the catalogue's safe mode guide covers getting there when you cannot see anything.
- On a desktop, check where the monitor cable is plugged in.A machine with a separate graphics card usually disables the ports on the motherboard. A cable moved from the card to the board — often when the machine was cleaned or repositioned — produces a permanently black screen on an otherwise perfect computer. Use the ports on the card.
Common mistakes
- Assuming the monitor is broken and buying a new one — A second cable and a second input take two minutes and are free. Monitors fail far less often than the cables and the port selection do.
- Ignoring the beeps — They are the machine's only way of talking when it cannot use the screen, and the codes are specific enough to name the failed part. People switch off the speaker or dismiss it as noise and then pay someone to work out what the beeps already said.
- Concluding the machine is dead because it is silent and dark at the panel — Check the external monitor first. A laptop with a failed panel is a fully working computer, and treating it as scrap is an expensive misdiagnosis.
If it doesn't work
No logo, fans at full speed immediately
Cause: The machine has failed its self-test — Fix: Full-speed fans from the moment of power-on, with no display, is a standard early-failure signature. Reseat memory, then look up the beep or blink code for your model.
Faint image visible with a torch
Cause: Backlight or its inverter has failed — Fix: The computer and the panel are both fine. On a laptop this is a repair, and a cheap one relative to the machine. Meanwhile an external monitor gives you a fully working computer.
Black screen but you can hear the login sound
Cause: The display output or the graphics driver — Fix: Windows is running. Try Windows key plus P to cycle display outputs, or Ctrl-Shift-Windows-B, which restarts the graphics driver without restarting the machine.
Black screen with a movable mouse pointer
Cause: The desktop shell has not started — Fix: Ctrl-Alt-Delete, Task Manager, run a new task and type explorer. If that brings the desktop back, the shell is crashing at sign-in and the cause is usually a startup program or a corrupted user profile.
Only black after the machine has been on a while
Cause: Overheating, or a failing graphics chip — Fix: Heat-related black screens follow a time pattern. The catalogue covers overheating laptops and thermal throttling; on a desktop check that the graphics card fan is turning.
Started right after installing a graphics driver
Cause: Wrong or broken driver — Fix: Safe mode, then roll the display driver back or uninstall it. Windows will fall back to a basic display driver that always works, which is enough to see what you are doing.
Questions people ask
What is the difference between this and a laptop that will not turn on at all?
If there are no lights, no fans and no sound, nothing is happening and that is a power problem — the catalogue has a separate guide for it. This guide is for a machine that clearly powers up and simply shows nothing, which is a much better starting position.
Where do I find what my beep code means?
On the manufacturer's support site for your exact model. Codes are not standardised across makers, so a generic list found by searching is often wrong. Dell, HP and Lenovo all publish theirs, and many recent machines blink the power or caps-lock light instead of beeping because they no longer have a speaker.
Could this be a dead hard drive?
Rarely, and the symptom is different — a failed drive normally produces a message about no boot device rather than a black screen with nothing at all. If you get any text on screen, read this guide's sibling on "no bootable device" instead.
Does a black screen mean I have lost my files?
There is no reason to think so. Nothing in this fault touches storage. Even in the worst case, where the motherboard has failed, the drive comes out and reads perfectly in a caddy.