Problems passing through GPU to an unRaid VM?

One of the most common problems I see people seeking help for on unRaid forums, reddit and discord is the thorny issue of GPU pass-through. People with the same problems tend to ask the same questions over and over, and, somewhat tired of providing the same troubleshooting steps over and over, I thought I'd write up the main pitfalls, and possible solutions.

Here are some steps to check before reaching out for help.

1. Have you done your research?

As noted, there's a ton of threads on unRaid forums covering this, many successfully resolved. Do conduct a search there. For example, searching 'problem with gpu passthrough' today produces 40 pages of results. Chances are, your issue has been raised and resolved several times before.

Another oft-posted remark is something along the lines of 'I followed spaceinvaderone's video, and it still doesn't work'.

In most cases where I've seen this, the user has incorrectly followed the video - missing a key step or subtle point. This is NOT a straightforward process. There are many variables involved and SpaceInvaderOne's videos are packed with information. He does an amazing job of explaining the complex process step by step, so make sure to rewatch these videos several times to ensure you haven't missed anything.

If you haven't been following one of his videos for GPU pas-through, why not? Get very familiar with the process and follow along before posting queries;

Here are some links to his channels;

https://forums.unraid.net/profile/67288-spaceinvaderone/

https://www.youtube.com/channel/UCZDfnUn74N0WeAPvMqTOrtA

https://www.reddit.com/user/spaceinvaderone/

Research done? Let's look at some of the common missteps....