Intel D975XBX2 PCIe Lanes

[BodoBaas]

I've been digging around different forums and the couple of reviews that exist for this MB to try and find out about how the PCIe lanes work when two PCIe video cards are installed. I will have two cards to run three monitors. What I am wondering is if anyone knows if the two primary PCIe slots will run in 16x and 8x mode with the two cards or will they automatically bump to 8x and 8x? Does anyone know, tried or know where I could find this out?

I will run my primary (center) monitor on the primary video card (79xx or 8xxx) and the two side monitors on the second video card (7600GT). I was hoping to keep the primary PCIe lane at 16x.

Thanks

 

[verncat05]

If you run two video cards in the two pci-express 16x slots, they will run in 8x and 8x mode. It's got nothing to do with the motherboard, it is a "limitation" (for lack of a better word) of the Intel 975X chipset.

Shawn

 

[BodoBaas]

I guess that is an advantage of the 680i.

Would a non-video card such as a raid controller or something let the two slots run at 16 and 8? Just curious.

 

[verncat05]

No, unfortunately. I think the best it can do is 16x for the video and the second slot would run at 4x.

Shawn

 

[BodoBaas]

So, do you think it would better to just have a single PCIe video card and a regular PCI video card for the secondary? Just how much of a performance hit will I notice if the primary video slot is in 16x mode vs. 8x?

 

[kirbyrj]

So, do you think it would better to just have a single PCIe video card and a regular PCI video card for the secondary? Just how much of a performance hit will I notice if the primary video slot is in 16x mode vs. 8x?

Not that much of a performance hit. I doubt you'd notice the difference.

 

[jsbond0071]

I know this is a really stupid question but do 2D users notice any shortfalls from x16 to x8 pci-express lanes.

Thanks.

James.

 

[Yreka]

I know this is a really stupid question but do 2D users notice any shortfalls from x16 to x8 pci-express lanes.

Thanks.

James.

I dont even think the 3d users notice. 16X16 is pretty much a fluff feature at this point.