a general question


Aug 15, 2006
hi guys
i have an asus p5b deluxe. i have read it from somewhere that if we run two cards in crossfire on this board at x16 and x4 respectfully, then the pci express slot 1x will be atomatically disabled while if we run it on x16 and x2, then pci express 1x slot will work. Is this true?


It all depends on how many PCIE channels are available in your particular chipset. I don't know offhand for your board but you just may not have enough to run that x1 slot with x4 at the same time.


Feb 9, 2007
You wouldn't be able to use the pci-e 1x slot with a second video card installed anyway it's, too close. I looked around but didn't find anything to support your statement but it wouldn't suprise me if it were true. I did a little more looking around and discovered that the 965 northbridge supports 16 pci-e lanes while the southbridge supports 6. When the second pci-e 16x slot is used it operates at 4x and any 1x slots are disabled. This is true of all boards with 2 16x slots.


Initially Intel's P965 Express chipset only supported a single PCI Express x16 videocard, however most current motherboards feature two physical PCI Express x16 slots. Given that the ICH8R southbridge has six PCI Express lanes, these have been utilized to support the second PCI Express x16 slot with 4 PCI Express lanes. It's not as ideal as both videocards received the full 16 PCI Express lanes each, but it works well enough with conventional videocards. The Gigabyte GA-965P-DQ6 is one of the few Intel P965 Express based platforms with two physical PCI Express x16 slots. It also has three PCI Express x1 slots, and these are disabled when a second videocard is installed because they share the same PCIe lanes with the second PCI Express x16 slot.

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