2x8 or 2x16 PCI-Express: Does it matter?

[GerryPers]

If you want to set up a dual graphics system for Pentium which motherboard is the best?

Asus P5N32 SLI Deluxe or a board based on the new 975x chipset?

P5N32 features 2x16 PCI-Express whereas 975x only supports

2x8 PCI-Express .

Is this difference significant at this point in time?

If not when will it be?

 

[chuckshissle]

I have the same question cause I have a GA-8N SLI mobo and has 8x dual graphics. I planning to upgrade to a 16x dual graphics but I don't know if there would be a significant difference in performance.

Has anyone currently using a 16x dual graphics and if so how fast is it compare to the 8x mobo?

 

[TheGreatGrapeApe]

Is this difference significant at this point in time?

If not when will it be?

It's only a difference for SLi/Xfire that doesn't use a bridge/dongle.

You MIGHT be able to get X1800/1900 and GF7800 cards to do multi GPU without the dongle with less of a performance hit, but I doubt either would perform as well as their current methods as they are hardware directed toward the dongle/bridge.

For pretty much every other application, there will be no difference, since the data doesn't saturate the 8 PCIe lanes the cards already use.

 

[mpjesse]

It doesn't make a noticable difference. Like TheGreatGrapeApe said, it could make a difference if you're not using the SLI bridge between the 2 cards.

Actually... ATI doesn't use a bridge... hmmm... I wonder if it makes a difference? ATI uses a DVI cable I think...

Well for sure, with SLI, it doesn't make a difference.

-mpjesse

 

[TheGreatGrapeApe]

It doesn't make a noticable difference. Like TheGreatGrapeApe said, it could make a difference if you're not using the SLI bridge between the 2 cards.

Actually... ATI doesn't use a bridge... hmmm... I wonder if it makes a difference? ATI uses a DVI cable I think...

Well for sure, with SLI, it doesn't make a difference.

ATI uses the d(a)ngle, it still feeds the cards the same way it does in SLi, but instead of a bridge the slave sends it's information along the dongle to the compositing chip. The X1600/1300 and even GF6200-6600 (IIRC) can send that information through the PCIe lanes to the compositing chip on the card, or to SLi chip interface (built into the core).

I don't think it makes a difference for the X1600 or GF6600, but it may mke a difference later, and it definitely would make a difference for that Dell monstrosity that uses both bridges and the pci lanes to communicate between all 4 chips. But heck that things more of a proof of concept than product worth worrying about.

 

[Heyyou27]

I think the SLI bridge is mainly for transferring the image from your second card, to your displaying card. This is what the split DVI cable does; although the SLI bridge might do a little more than just that.

 

[pwnage]

eventualy you will se the proformance gain but as of right now there is much of one.

 

[mopeygoth]

as much difference as adding 1mhz core clock

unless you need a ton of lanes for eg. raidcontroller/ethernet-workstation card it is pointless

i tried running my (single) card in 8x mode versus 16x mode, and there was nearly no difference in scores, game experience was exactly the same. I am actually running in 8x mode now because of a huge passive nb heatsink is blocking my top 16x slot w. nV5 silencer installed