PCI Express 3.0 and Ivy Bridge Questions

McSaggler

Distinguished
Jul 25, 2008
11
0
18,510
Hello,

I'm slightly confused on the whole Ivy Bridge PCI-E 3.0 support and the 16 lane maximum, so I had a few questions.

If I run two graphics card with PCI-Express 3.0 at x16 each, will the processor only accept x8 from each card? If this is true, there would be no point in getting a motherboard such as http://www.newegg.com/Product/Product.aspx?Item=N82E16813131822 which supports x16 each lane in PCI-Express 3.0, when running SLI or CrossfireX. It would make more sense to get something like http://www.newegg.com/Product/Product.aspx?Item=N82E16813131821 which supports x8 each lane in PCI-Express 3.0 (for a total of 16 lanes for the processor, which is the cap for the processor).

In addition, what if I added a sound card to a PCI-E x1 slot? Does that take up a lane to the processor and thus only only allowing 15 lanes for the GPU's?

Any help would be appreciated.
 

benikens

Distinguished
Jun 8, 2011
324
0
18,810
I'm not the most knowledgeable person about this, but I do know that often high end motherboards (e.g., $250+ models) will have extra chips on the board itself that increases the amount of PCI-e bandwidth.

^ This is true, with Sandy-Bridge you could get a motherboard with a NF200 chip on it and get dual x16 performance. Also on newegg if you click the 'Details' tab and scroll down to expansion slots it tell you the layout of your PCI-e lanes in different configurations e.g. the ASUS P8Z77 WS LGA 1155 Intel Z77 SATA 6Gb/s USB 3.0 ATX Intel Motherboard you linked has the following options x16/x16/0/0 or x16/x8/x8/0 or x8/x8/x8/x8 which means it will run PCI-e 3.0 at full bandwidth using 2 Cards in SLI or Crossfie, whether or not you need the bandwidth is a different matter entirely.
 

McSaggler

Distinguished
Jul 25, 2008
11
0
18,510


Thanks for your reply. I did see this but I was not entirely sure if it was accurate. When it said x16/x16/0/0 for PCI Express 3.0 I thought it would still be capped by the Ivy Bridge processor. Apparently this motherboard implements the PLX chip to allow more lanes of PCI Express. Is this true?