Unfortunately, I don't have another Nvidia card lying around. This was the only graphics unit in my unraid build, since I opted for a cpu without iGPU.
It turns out that after trying the card on a windows machine, none of the Nvidia drivers actually work, even when going back as far as v353, they just turn a black screen, so unless I'm misunderstanding, there is probably something fundamentally wrong with the card. Installing the drivers just throws errors and doesn't actually run other than a rudimentary display via microsoft compatible drivers. I remember a few years back the card used to work properly on that machine, so the card probably got messed up since then. But the card is still good to use to watch unraid booting and changing bios settings so there's that.
Thanks for all your help in diagnosing this with me. I should have caught that the graphics card itself was problematic by testing it with the nvidia drivers in Windows beforehand rather than assuming it worked because it was detected by windows and unraid. Hopefully I'll be able to get a new Nvidia card soon so I can finally make use of your awesome plugin!!