Why are some Motherboards able to support 4 way sli/crossfire while cpu only has 16 pcie lanes?

Solution


Because the Chipset has an additional 24 PCIe lanes used for other devices such as the M.2 drives, sata ports, etc.

In this case the 16 pcie lanes of the CPU are split amongst the first 2 slots, and 16 additional are split from the motherboard PCH count of 24 into 2 slots. Hence you get 4 way SLI with 4 x8 lanes.

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Because the Chipset has an additional 24 PCIe lanes used for other devices such as the M.2 drives, sata ports, etc.

In this case the 16 pcie lanes of the CPU are split amongst the first 2 slots, and 16 additional are split from the motherboard PCH count of 24 into 2 slots. Hence you get 4 way SLI with 4 x8 lanes.
 
Solution