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

jmke · 10th September 2009, 10:34

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

jmke · 10th September 2009, 11:08

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

10th September 2009, 10:34	#1
jmke Madshrimp Join Date: May 2002 Location: 7090/Belgium Posts: 79,022	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 __________________

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