I've been using Bitnand 8GPU mining 4U rack system. It comes with a riserless MB with 8 slots, supporting AMD and Nvidia GPUs. The system also supports the latest RTX 2080 and 2080Ti series.
Imgur album of the system:https://imgur.com/a/7YGrqcr#dkoeOAD
Available on bitnand.com. Purchase Bitnand mining systems only through authorized dealers or direct:https://www.bitnand.com