40 lanes is a common limitation on consumer chipsets and core i7's (the Z170, x99 and z97 are commonly used for DL builds) but as you said pairs of older Xeons

40 lanes is a common limitation on consumer chipsets and core i7's (the Z170, x99 and z97 are commonly used for DL builds) but as you said pairs of older Xeons make more available: https://www.microway.com/hpc-tech-tips/common-pci-express-myths-gpu-computing/ https://www.microway.com/hpc-tech-tips/common-pci-express-my... Above that, you need to look at c612: https://www.supermicro.com/products/motherboard/Xeon/C600/X10DRH-iLN4.cfm https://www.supermicro.com/products/motherboard/Xeon/C600/X1...