Building a Multi-GPU Deep Learning Machine on a budget

PCI Express slots on the motherboard can be wider then the number of lanes connected For example a motherboard can have x8 slot with only x1

Review this - is You can use PCIe cards of a lower lane width in a higher lane width slot PCI-Express

gpu blocking pcie slot As you can imagine, and slot GPUs are slightly widertaller than slot models, with a modern example being the EVGA GeForce RTX 2080

gpu slot size There is some compatability for PCI-E and You can run a PCI-E card in a PCI-E slot but you will do so at a reduced speed