PC won't boot after installing a new GPU

New card in. Fans spin. Nothing on screen. It's one of the most common calls we get, and most of the time it's not the GPU.

1. Check which port you're plugged into

This catches more people than it should. If your CPU has integrated graphics, your motherboard has its own display outputs - and those stop working the moment a dedicated GPU is installed. Make sure your monitor cable is plugged into the GPU itself, not the motherboard.

If your CPU has no integrated graphics (most Ryzen 5000/7000 series, Intel F-series chips), the motherboard ports will never output a signal. GPU only.

2. Check the power connectors

A GPU that isn't getting enough power will either fail to boot or crash immediately under load. Make sure every PCIe power connector on the card is fully seated - they click in. If your card needs two 8-pin connectors and you've only plugged one, it won't boot.

Also worth checking: avoid daisy-chaining two connectors off a single cable if your PSU cables support it. Use two separate cables from the PSU where possible. Shared cables can't always deliver the current a modern GPU needs.

3. Re-seat the GPU

Remove the card and put it back in. The PCIe slot has a retention clip at the end - it needs to click. A partially seated GPU is electrically connected enough to look installed but not enough to actually work.

While it's out, clear any dust from the PCIe slot with a puff of air.

4. Clear the CMOS

Your motherboard stores its settings in a small memory chip kept alive by a coin cell battery. If those settings have got confused by the hardware change, clearing them resets everything to factory defaults and often resolves a no-boot after a component swap.

Look for a Clear CMOS jumper on the motherboard (usually labelled JBAT1 or similar), short it for a few seconds with the PC unplugged, then remove it. Alternatively, remove the coin cell battery for 30 seconds with the machine unplugged. Either method works.

5. Update the BIOS

Some older motherboards don't support newer GPUs without a BIOS update. If your board is a few years old and the GPU is recent, this is worth checking. You'll need to boot using integrated graphics (if your CPU has them) or borrow a known-working older GPU to get into Windows and run the update.

The motherboard manufacturer's website will have the latest BIOS and flashing instructions. Don't skip this step if the card is a recent release.

6. Check PSU wattage

A PSU that's undersized for the new GPU won't have enough headroom to POST reliably. Add up the rough TDP of your CPU and GPU, add 20% for headroom, and compare that to your PSU's rated wattage. A system with a Ryzen 5 and an RTX 4070 needs at least a 650W PSU. Cutting it close means instability under load, or a no-boot on cold start.

An old PSU that's technically powerful enough on paper can also cause issues - capacitors degrade over time and a PSU that's five-plus years old may no longer deliver clean power under a higher GPU load than it's used to.

When to stop and send it in

If you've worked through all of the above and still have nothing, the most likely culprits are a dead GPU (test it in another machine if you can), a PCIe slot fault on the motherboard, or a PSU that's failing under load rather than at idle.

We can bench-test GPUs, diagnose PCIe slot issues at component level, and identify PSU faults without guesswork. If your new card is genuinely faulty, we can confirm that in writing so you can make a warranty claim with the retailer.