Passing through a GPU on Unraid is usually a pretty easy task. Issues are easily solved as long as it’s in one of the “GPU” / main PCIe slots on most motherboards. There are some issues using it in the primary slot which are easily overcome. I discussed in my unRAID Pascal GPU Passthrough guide. However, for more advanced setups, you’ll need to start passing through other PCIe devices to virtual machines. This starts to get a bit more tricky and the many guides have some shot-gun approaches to solving the problems associated with these advanced setups. In order to maximize system stability, you’ll want to avoid these shot-gun approaches and the pitfalls associated with them. In this post I’ll give you a basic understanding of PCIe and IOMMU groups. Then discuss one of the more commonly touted “solutions” and the pitfalls associated with it.