I've got a GTX 1650 and a Ryzen 5 Pro 4560G with a B450M motherboard and a 450W power supply. Recently, I upgraded to an RX 7800 XT and also got a new power supply and case. Unfortunately, my system won't use the new GPU; the display always comes from the motherboard's integrated graphics. I've tried every possible fix—adjusting BIOS settings, reinstalling drivers, disabling the integrated graphics drivers, tweaking registry settings, and checking all connections. The GPU shows up in AMD Adrenaline before POST but then it just defaults back to the motherboard. I'm really stumped and considering taking it to a repair shop, but they're not very trustworthy around here. Any suggestions would be greatly appreciated!
5 Answers
It might help to try testing the GPU in another PC if you have access to one. Also, do you notice any fans or lights on the GPU when you power it on? What's the wattage of the new power supply?
You might want to try a different display cable or port, or even use a TV as a monitor to see if that works. If you still have no signal, the issue could be with the GPU or possibly the PSU.
Yeah, I've been thinking about buying a DisplayPort cable to see if that helps.
Check if the GPU shows up in Device Manager. If it's listed there, make sure the right drivers are installed. Have you disabled the integrated GPU in the BIOS? Sometimes, it can help to disconnect the power supply for a bit after disabling it.
Yes, it appeared in Device Manager and the drivers are good. But when I disable the iGPU, I lose signal on both outputs, even after removing the motherboard battery.
Look for any bent pins on the CPU socket; those can cause major problems. Have you checked that?
I don't see any bent pins, but I might need to double-check.
Make sure you're connecting the monitor to the GPU, not the motherboard. Also, verify that the GPU is properly connected to the PSU. That's a common issue!
Yep, I’m connecting the monitor to the GPU, but it never shows anything. I’ve checked the PSU cables multiple times.

It doesn't have a light, but the fans spin up at startup and then stop. The new PSU is a 650W Cooler Master, so I think it should be decent.