Question Unusual hardware meets modern GPU

[MTYates]

I recently purchased an RX 6600 XFX and am trying to get it to work on my computer. When plugged in, no error codes of any kind play or show up on the LED POST codes screen, nothing unusual at all, but there is zero video output from the gpu, the monitor i have does recognize a connection of some kind, but the screen stays black with no BIOS screen or anything of the sort. System was fully functional before putting new GPU in
CPU: 2x Intel Xeon e5 2630-v3
Motherboard: Mysterious Chinese Motherboard (MCM) X-99 with American Megatrends BIOS
Ram: 2x Crucial Pro DDR4 16GB
Previous GPU: Nvidia GT 240
PSU: Gigabyte UD750GM
System was perfectly functional, then i decided to uninstall the GPU drivers for the GT 240, placed the RX 6600 in, and then zero output. Note that when I installed the GT 240 into this system, it had no drivers, and would still output video, albeit more slowly. I also tried a fully separate RX 6600 XFX earlier with the computer, and had the same issue with no output. That was before i had removed the GT 240's drivers, so I put the GT 240 back in and it worked fine that time. Now neither the 6600 or 240 will show anything on my monitor despite zero complaints from the Motherboard or monitor.
Help would be much appreciated, thank you

 

[Lutfij]

Welcome to the forums, newcomer!

First thing you can do is check and see if the motherboard is pending any BIOS updates. Then see if your OS is pending an update, alongside chipset drivers. Following all of that, use DDU to remove all GPU drivers(Intel, AMD and Nvidia, Nvidia) in Safe Mode, then manually reinstall the latest GPU driver sourced from AMD's support site in an elevated command, i.e, Right click installer>Run as Administrator.

PSU: Gigabyte UD750GM
How old is the PSU and what did it power throughout it's lifetime?

Now neither the 6600 or 240 will show anything on my monitor despite zero complaints from the Motherboard or monitor.
The processor lacks an iGPU neither does the board have an GPU chip onboard, you won't get display out off the motherboard, no matter what you try. Looks to me like your board croaked due to a corrupt BIOS...perhaps.

Mysterious Chinese Motherboard (MCM) X-99 with American Megatrends BIOS
Got a link to said motherboard?

 

[MTYates]

Link to the motherboard: https://www.ebay.com.au/sch/i.html?....m570.l1313&_nkw=lga2011+v3+dual+cpu&_sacat=0
with the black and orange colour scheme, it was purchased new and when opened seemed to be completely unused, i went searching on the internet and found this: https://miyconst.github.io/hardware/cpu/intel/motherboard/2023/11/18/chinese-x99-post-codes.html when the computer reached the black screen after bootup, the LED on the motherboard showed AA, seemingly indicating normal operation
The power supply is also brand new, bought last month. it has only ever powered this system

And i forgot to mention, the OS is Windows 10 Pro 64 Bit, it did have pending updates, and when i was previously in BIOS before the issue occured, i remember the Motherboard BIOS seeming reasonably recent.

 

[MTYates]

Update: I've just pulled out the cmos battery for a few minutes, reseated the ram, rechecked the power cables and after placing the cmos battery back in the poor thing just stutters and shows error code FF 'CPU error or bios installation'.
I folded the clip that lets you take the CMOS battery out over the battery to keep it in place more firmly, then let it reboot itself showing the error code FF again a couple of times, until the 3rd boot, where i saw the BIOS screen and heard the startup beeping, then it rebooted again and it seems that everything is alright with the MCM. Problem solved and back into windows