Why is my monitor screen going into standby after plugging in my newly built pc.

Hi Sebastian Wakefield,

Welcome to Microsoft Q&A!

The fact that your monitor goes into standby mode after 3 seconds when connected via DisplayPort to your newly built PC usually means it's not receiving a valid video signal. To better help you, I'd like to ask if you can detect your monitor at all? In the meantime, here's something you must check:

1 - Basic connections:

• Make sure your monitor is set to the correct input. If you plugged in a DisplayPort cable, use the monitor's buttons to manually select the DisplayPort input source. It doesn't automatically switch sometimes.
• Ensure the power cables are firmly plugged into both the wall outlet and the monitor, in which the main power cable is secure in the power supply unit (PSU).
• Test with:
  • Another DisplayPort cable if you have one.
  • A different DisplayPort or HDMI port on your graphics card.
  • An HDMI cable instead. This can tell you if the problem is with the DisplayPort.

2 - Internal hardware connections

• Graphics card: Is your monitor plugged into the graphics card and NOT the motherboard? If your CPU does not have integrated graphics, the motherboard ports will do nothing.
  • Turn off the PC, unplug it, press the power button to drain residual power, then open the case.
  • Push down on the graphics card until it clicks firmly into the PCIe slot.
  • Also ensure the PCIe power cables from the PSU are firmly connected to the card.
• Reseat the RAM:
  • Turn off and unplug the PC.
  • Remove the RAM sticks and then firmly push them back into their slots until the clips on both sides click into place.
• Try using just one stick of RAM in the primary slot (check your motherboard manual).

3 - Perform a Power Cycle to clear any temporary electrical issues

• Turn off the PC and monitor, unplugging both from the wall outlet.
• Press and hold the PC's power button for 30 seconds to drain any remaining power
• Wait a couple of minutes, then plug everything back in and turn on the PC
• Check closely for physical hints like small beeping sounds or LEDs signal
• Try connecting with the monitor again.

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Are you actually able to get into Windows, or is the monitor going to standby before you can boot into Windows?

1

If you are not able to get into Windows, try connecting the monitor to all available video output ports both on the graphics card and on the motherboard to test if you can access Windows.

If not, try resetting BIOS using this method;

Remove the power cable from your laptop.

Press and hold the power button on the case of your laptop for 30 seconds.

Wait 30 minutes

Reconnect the power cable and start your PC.

2

Once you can get into Windows, go to the support page for your graphics card (if you have one) and re-install (not update the graphics drivers from there), also, if there is integrated graphics, re-install the drivers for that from the motherboard support web page.