16x vs 8x

[Qtip1318]

hi guys i have been looking at some motherboards and i just wanted to know what the bottle neck would be when they talk about running more then one video card is sli or crossfire, what i mean by this is if you would have two 780ti's and where running them in sli at 16x/8x or 16x/16x. is there going to be a performance advantage that you can see? or what effect dose it even have 

[coen113]

no, it will be fine

[Tmh85]

no it will be A O K

[WoodenMarker]

Gpus have yet to fully saturate pci-e 2.0 x8.

[jscho]

Zero bottleneck. AMD cards can run on 4x with no issue. The PCIe bus has so much bandwidth, GPU's can't use all of it.

[Qtip1318]

well thank you every one for the help… Maybe this is a dumb question but dose anyone know why they would use a 16x slot if they don't need all the bandwidth

[Titanicium]

well thank you every one for the help… Maybe this is a dumb question but dose anyone know why they would use a 16x slot if they don't need all the bandwidth

 

Because of all the #YOLOSWAG

 

No honestly: No idea, but it is most likely just a marketing scheme so that people may think that they actually need it. No GÅUs today can saturate a PCI-E 2.0 16x slot which is the same as a PCI-E 3.0 8x slot

[brob]

well thank you every one for the help… Maybe this is a dumb question but dose anyone know why they would use a 16x slot if they don't need all the bandwidth

 

One doesn't need to come close to saturating a bus to derive benefit from its faster speed. While the benefit is small, faster transmission does mean better throughput.

 

Add up small improvements here and there in a system and the net result is a better performing rig. For the average enthusiast it is hardly worth it. But there are those who derive great pleasure out of pushing the envelope. There are also applications where even marginal performance improvements can pay for themselves.

[-rascal-]

We technically don't need PCI-Express 3.0 yet, but the "inventors" decided to push that forward anyways ($$).

It's also hype so people will get new motherboards (Intel, harrrooo! I see youuu!)

The performance difference, if there is any at all, is very tiny. We are speaking 1%-5% in most situations (which is like what...1 - 3 FPS?).

 

nVidia SLi requires at least X8 slots (X16 or X8). If X8 is too much of a bottleneck they wouldn't suggest it.

 

The theoretical bandwidth for PCI-Express is double every revision.

Examples:

PCI-E X16 1.0 = PCI-E X8 2.0

PCI-E X16 2.0 = PCI-E X8 3.0

 

This is why AMD didn't really jump on the PCI-E 3.0 bandwagon as quick as Intel...since most of their higher-end chipset motherboards (i.e. 990FX) has enough PCI-E lanes to run two (2) PCI-E X16 2.0 slots at full speed (with a few extra left over).

 

If an Intel board does PCI-E X8 3.0 + PCI-E X8 3.0 with SLI / Crossfire...it's the same as a AMD board with PCI-E X16 2.0 + PCI-E X16 2.0

[Qtip1318]

We technically don't need PCI-Express 3.0 yet, but the "inventors" decided to push that forward anyways ($$).

It's also hype so people will get new motherboards (Intel, harrrooo! I see youuu!)

The performance difference, if there is any at all, is very tiny. We are speaking 1%-5% in most situations (which is like what...1 - 3 FPS?).

 

nVidia SLi requires at least X8 slots (X16 or X8). If X8 is too much of a bottleneck they wouldn't suggest it.

 

The theoretical bandwidth for PCI-Express is double every revision.

Examples:

PCI-E X16 1.0 = PCI-E X8 2.0

PCI-E X16 2.0 = PCI-E X8 3.0

 

This is why AMD didn't really jump on the PCI-E 3.0 bandwagon as quick as Intel...since most of their higher-end chipset motherboards (i.e. 990FX) has enough PCI-E lanes to run two (2) PCI-E X16 2.0 slots at full speed (with a few extra left over).

 

If an Intel board does PCI-E X8 3.0 + PCI-E X8 3.0 with SLI / Crossfire...it's the same as a AMD board with PCI-E X16 2.0 + PCI-E X16 2.0

thanks man that is really help full