Question Computer won't connect to display after installing new GPU

Oct 25, 2021
Half a year ago I built a PC that turned on properly, except I couldn't install windows 10 because my GPU wasn't compatible. I don't blame it because I had a Raedon 5450 HD. I then bought a new 3070 TI after the market went down, but since installing it, now neither of my GPUs work. Neither will connect/produce a signal to my monitor, which works fine when I connect it to my laptop. When I had my old GPU plugged in before I got my new one, I was able to boot into BIOS and saw everything appear as it should. I again got stuck on the screen telling me my GPU wasn't compatible.

My CPU does NOT have integrated graphics and I have tried both GPUs in both PCI-E slots.

Any ideas on what might be causing this? I already tried unplugging the install key to boot into BIOS.

CPU: Ryzen 7 5800x
CPU Cooler: Cooler Master ML240L RGB V2
Motherboard: ROG Strix B550-F
Memory: 2 x G.Skill Ripjaws V 16 GB
Storage: WD Blue 1 TB M.2 NVME SSD
GPU: Radeon HD 5450 and 3070 TI (one or the other)

My system is rated for 533 W according to PC Part Picker.


Oct 11, 2015
The post screen indicates that UEFI isn't being supported by the video card. This should not be the case with the 3070, but would more than likely have been the case with the 5450 (It probably ran in legacy support and why Windows 10 didn't like it). If this screen is showing up with the 3070 only I would try to reset bios or force UEFI mode. Until UEFI picks up on that card Windows more than likely won't recognize it. If both cards are in pull the 5450 because it is probably causing the conflict.
The cable is connected via HDMI to the computer and via DVI to the monitor.
Yes, it is connected to the graphics card,
I am using HDMI on my GPU.
No adapters, this is just the cable that came with the monitor

I've never used but I hope this works. I have not been able to get to this point since I installed the new GPU as it doesn't even connect.
Looks like you installed your Windows with CSM enabled for legacy booting with your HD 5450. You will need to do some tweaking to Windows so that it will boot in UEFI mode if you want to keep everything as it is but it can be difficult to do.

You could just reinstall Windows on the drive with UEFI enabled in bios and continue on using it with the 3070 TI, but that doesn't solve the issue of the drive not being activated with GPT partiton table for full UEFI compatibility.

With CSM legacy mode enabled, you activated your drive with MBR partition table which does not have full UEFI compatibility, but will still work with UEFI mode enabled in bios and should allow your 3070 TI to function (since it's looking for UEFI in bios) as long as Windows is tweaked to boot in UEFI mode.