Computer Won't Turn On? PC Fixes That Keep Your Files Safe

When a computer won’t turn on, the cause is usually somewhere along the power path: the outlet, the power strip, the switch on the back of the power supply, the wire from the case’s power button, the power supply itself, or the motherboard. Desktop PCs are built from standard parts, which makes them easier to troubleshoot than laptops, and it means the drive holding your files is almost always a separate part that survives whatever failed. This guide is for desktop towers and all-in-one PCs; if you have a laptop, see laptop won’t turn on.

Computer won’t turn on, or turns on with no picture?

These are different problems:

• Nothing happens: no fans, no lights, no sound. Work through the power checks below.
• Fans and lights come on, but the monitor is black: the PC has power. The problem is the display connection, graphics, memory, or motherboard. See PC turns on but no display.
• It starts, then shows a message like “Reboot and select proper boot device”: the hardware works but can’t find something to start from. See reboot and select proper boot device.
• It turns on for a second, then shuts off: often a power supply, short circuit, or seating problem.

Check the outlet, strip, and cable

1. Plug the PC directly into a wall outlet you’ve tested with a lamp or phone charger. Power strips and surge protectors wear out or get switched off by a stray foot.
2. Reseat the power cord at both ends. The plug at the back of the PC can work loose.
3. Try a different power cord. Desktop power cords are standard and cheap to swap.
4. On a UPS (battery backup), bypass it for now. A failed UPS battery can stop the outlet from passing power.

Check the power supply switch

Most desktop power supplies have a rocker switch on the back, marked I (on) and O (off). It’s easy to bump when moving the PC. Set it to I.

Some older power supplies also have a red 115V / 230V voltage selector. In the US it should be set to 115V. If it’s on 230V the PC may not start; if you find it set wrong, don’t keep trying, since a supply switched to the wrong voltage can be damaged.

Check the front power button connection

The power button on the case is connected to the motherboard by a small two-pin wire, usually labeled PWR SW or POWER SW, on the front-panel header. If the PC was recently moved, cleaned, or upgraded, it may have come loose.

With the PC unplugged, open the side panel and check that the connector is pressed onto the pins your motherboard manual shows. If you’re not comfortable working inside the case, this is a good point to stop and get help.

Look for motherboard lights and listen for beeps

With the case open and the PC plugged in:

• A standby light on the motherboard means the power supply is delivering standby power. No light at all points to the power supply, the cable, or the outlet.
• Debug LEDs: many modern motherboards have small LEDs labeled CPU, DRAM, VGA, and BOOT. The one that stays lit shows where startup stopped. Some boards have a two-digit code display instead.
• Beep codes: if your board has a speaker, the pattern of beeps points to a fault. The meanings differ between manufacturers, so look them up in your motherboard manual.
• Brand-name desktops from Dell, HP, and Lenovo often blink the power button light in a pattern for the same purpose. Check the manufacturer’s support site for your model’s table.

Test or swap the power supply

The power supply is one of the most common reasons a desktop won’t turn on at all.

• The simplest test is a swap. If you have a known-good power supply, or a friend with one, connect it and try again.
• The paperclip test is a common way to check whether a power supply turns on outside the PC: with it unplugged from the wall and disconnected from all components, a paperclip bridges the green (PS_ON) wire and a black ground wire on the 24-pin connector, then the supply is plugged in and switched on to see whether its fan spins. Only do this if you’re experienced and careful. It proves only that the supply can start, not that it delivers stable power under load. Never open a power supply. Capacitors inside can hold a dangerous charge even when it’s unplugged.

A burning smell, a pop, or smoke means stop. Unplug the PC and don’t try again.

Reseat RAM and check connections

If the PC powers on but won’t start properly:

1. Unplug the PC and touch bare metal on the case to discharge static.
2. Remove and firmly reinsert each RAM module until the clips snap. Try one module at a time if you have several.
3. Check the 24-pin and CPU power connectors on the motherboard and the power connectors on the graphics card.
4. Make sure the monitor is plugged into the graphics card, not the motherboard, if you have a separate card.

Your files usually survive a dead PC

A failed power supply or motherboard almost never erases the drive. In a desktop, the SSD or hard drive is a separate component held in by screws and a cable or two, so it’s usually the easiest part to rescue.

• Move the drive to another computer or read it with a USB adapter or enclosure. See how to get files off a dead computer.
• BitLocker: if Windows encryption was on, you’ll need the 48-digit recovery key to read the drive elsewhere. See where to find your BitLocker recovery key.
• Multiple drives: if your PC used RAID or Windows Storage Spaces, keep the drives together and don’t connect them to another PC one at a time.
• If the failure involved a surge, a pop, or a burning smell, the drive’s own circuit board may also be damaged. Don’t plug it into anything; that’s a job for a lab.
• If the drive clicks, isn’t detected, or disconnects, stop. Repeated attempts can make recovery harder.

The bottom line

When a computer won’t turn on, plug it into a known-good wall outlet, check the power supply switch and cord, confirm the front power button cable is connected, and read the motherboard’s lights or beep codes. Swapping in a known-good power supply is the safest way to test it. Your files are almost always on a drive that survived, so move it to another PC if you need them now.

If the drive has failed or was damaged along with the PC, our desktop and PC data recovery service recovers data from dead computers and their drives for one flat $1,200 price for a single device. Shipping is free and prepaid, and you pay nothing unless the recovery succeeds.