4CPU sockets !=> 4x x16 cars. It always depends on the number of PCI lanes for each processors. Check i.e. these 2 E7 Xeons: http://www.intel.com/content/www/us

4CPU sockets !=> 4x x16 cars. It always depends on the number of PCI lanes for each processors. Check i.e. these 2 E7 Xeons: http://www.intel.com/content/www/us/en/products/compare-products.html?productIds=93811,93804 http://www.intel.com/content/www/us/en/products/compare-prod... Both have max 32 PCI Express lanes - so you can theoretically hang max 2 PCIx x16 cards off each CPU, but as few of the lanes is reserved for other peripherals, in 4GPU/CPU setup they will practically run at lower speeds, ie 8/8/4/4. However, using system with PCIe root complex [1] can improve the GPU<->GPU communication speed. [1] https://www.microway.com/hpc-tech-tips/pci-express-root-complex-confusion/ https://www.microway.com/hpc-tech-tips/pci-express-root-comp...