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No picture after plugging your PC back in

Moved your computer, or just got it back from us, and the screen stays black? It's almost always one of two cables.

Display problemsAbout 5 minuteseasy

Nine times out of ten this isn’t a fault. The computer is running perfectly well and simply sending the picture somewhere you aren’t looking.

There are two causes, and between them they account for almost every “it was working before I moved it” call we get.

Cause one: the monitor is plugged into the wrong socket

If your PC has a graphics card — and every gaming machine we build does, along with most of the higher-end office ones — then the back of the case has two sets of video ports. One set belongs to the motherboard. The other belongs to the graphics card.

When a graphics card is fitted, the motherboard’s video ports are usually switched off. Plug into them and you get nothing at all, no matter how healthy the machine is.

The back of a desktop PC, showing motherboard ports and graphics card ports The motherboard's video ports sit in the cluster at the top and are usually switched off when a graphics card is fitted. The graphics card is the horizontal card below, and its ports are the ones the monitor should be plugged into.HDMIDPDP · DP · HDMIPowerNot theseMotherboard video ports. Usuallyswitched off if a card is fitted.Plug your monitor hereThe graphics card — the horizontalcard lower down the back.One cable per monitorHDMI and DisplayPort into thesame screen makes Windows thinkthere are two of them.
Port layouts vary between machines — what matters is that the graphics card is the horizontal card lower down, and that's where the monitor goes.

The graphics card is the horizontal card sitting lower down the back of the case, and its ports are the ones you want. The motherboard’s ports are up in the cluster at the top, alongside the USB sockets, the network port and the round audio jacks.

If your machine came from us, look for a sticker. We put one over the motherboard’s video ports on new builds saying not to use them, and another by the graphics card showing where the monitor goes. Stickers do fall off and staff are human, so their absence doesn’t mean you’re in the right place.

What to do

  1. Turn the computer off at the wall.
  2. Follow the monitor cable to the back of the PC and see which set of ports it’s in.
  3. If it’s in the top cluster, move it to the horizontal card lower down.
  4. Turn it back on.

That’s usually the whole fix.

Cause two: one monitor, two cables

The other common one. A single screen gets connected twice — HDMI and DisplayPort into the same monitor, often because both cables were already there and it seemed sensible to use them.

Windows doesn’t see one monitor connected twice. It sees two monitors, and it cheerfully puts your login screen, or your taskbar, or the window you’re hunting for, onto the one that doesn’t exist.

The symptom is distinctive: the machine boots, you can see something, but the login prompt never appears — or programs open somewhere you can’t get to.

What to do

Unplug one of the two cables. Either one. You only need a single cable per screen.

If you have genuinely got two monitors, then one cable goes to each — not two cables to one and none to the other.

Still black after all that?

Then it’s worth a proper look, and there are a few things to check before you bring it in:

  • Is the monitor switched on at its own power button, and plugged in at the wall?
  • Is the monitor set to the right input? Most have a source or input button that cycles through HDMI 1, HDMI 2, DisplayPort and so on.
  • If the PC was moved, did anything come loose inside? Transport can unseat a graphics card. Don’t force anything — that’s a job for the bench.

If none of that brings it back, stop there and give us a call. Bring the tower in, and bring the monitor cable with it — it’s a five-second test for us and cables do fail.