Madshrimps Forum Madness - Not all 2nd PCIe "x16" Slots On P55 Motherboards Created Equal?

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Not all 2nd PCIe "x16" Slots On P55 Motherboards Created Equal?

An analysis of the tech specs of the 30 LGA1156 motherboards from ASRock, ASUSTeK, Gigabyte, MSI and Intel with a second x16 PCI-Express port shows up an aspect of the spec that may go unnoticed at first but which is nevertheless important. On 12 of these motherboards the second x16 PCI-Express is not connected from the LGA1156’s processor to the PCI-Express controller with 8 lanes (the 1st PCI-E port is 8 lanes) but with 4 to the P55 Express.

What’s more the lanes linked to the LGA1156 processor function at 5 GT/s and those linked to the P55 at 2.5 GT/s: this means one x16 PCI-Express port at x4 with the P55 functions at 1 GB/s in each direction as against 4 GB/s when at x8 with the processor!

http://www.behardware.com/news/10399...x16-pci-e.html

Quote:

I know they're incorrect on the Asus P7P55D EVO and the Asus P7P55D PRO. Both of those boards are x16 for a single card, X8, x8 for dual cards. BUT, the caveat is you must use the blue and black PCI-e x16 slots for the x8, x8 function. The white PCI-e x16 slot on both of those boards function as an x4 electrically. Maybe that's where they're making their mistake....using the wrong slot for Crossfire/SLI.

http://www.xtremesystems.org/forums/...&postcount=185