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PCIe x16 (at x4 speed) ?!

4 posts · originally from https://geek.digit.in/community/threads/pcie-x16-at-x4-speed.122762/

V
Vivek.28 Original post #1
Nov 23, 2009 at 9:19 PM
I have a Mercury PI945GZD motherboard. It has a PCIe x16 slot. But when I see the manual it says: PCIe x16 (at x4 speed)

What does this 'at x4 speed' mean ?

I was planning on buying a PCIe x16 based graphics card, but now I'm confused !
asingh
asingh #2
Nov 23, 2009 at 9:44 PM
^^

The PCI.Ex16 standard has 16 full duplex lanes (serial) which channel via the Northbridge to the GPU card.

Your motherboard is setup in such a way, that only "4" of this lanes are available for data exchange. So theoretically this slot will run at 25% levels only. You can buy a GPU but it will be substantially held back due to this limited architecture.
V
Vivek.28 #3
Nov 23, 2009 at 11:10 PM
Ohh !! Thanks for the reply...