6700k vs 6800k PCi x16 SLI

[mmedeiro]

Hi all

I'm looking to upgrade from a LGA 2011 4820k. I always run my GPU's in SLI, so PCi lanes are important. I'm a little confused regarding the PCi lanes on each chip set.

The x99 says its has up to 40 lanes but only with a compatible CPU but it seems like the 6800k is only a 24 lane chip and therefore ill be running 16x 8x?

I'm not finding any 2011-v3 with 2 16x PCI slots. Again 16x 8x.

Am i confused, neither CPU is capable of running 2 GPUs @ 16x?

Its been a while since i researched this. Is 8x the max speed ill need for a GPU?

My current system
x79 Sabertooth
i7 4820k
2x MSI 980ti GC in SLI
32 gb Ballistix sport 1600
Rosewill Lightning 1300w

Thanks

 

[ryguybuddy]

No, neither CPU can run both at 16X, although I see no reason why that would be a problem. The only GPU to saturates the PCIe 3.0 x8 interface is the Nvidia Titan X (pascal) at 4K, and I am assuming you don't have two of these.

If you really want both cards to run at 16x, get the 6850K instead. It is pretty much the 6800k but with a higher clockspeed and 40 PCIe lanes.

 

[Ecky]

The performance difference between 8x and 16x is negligible. SLI must be symmetrical, so if you don't have the lanes for 16x/16x, it'll run 8x/8x.

-6700K has 20 lanes, and could run two cards in 8x/8x with 4 lanes leftover for whatever - an M.2 SSD?

-6800K has 28 lanes, and could run two cards in 8x/8x with 12 lanes leftover for whatever.

-6850K has a full 40 lanes and could run two cards in 16x/16x, but the performance difference is negligible.

That said, a single 1080 will probably be faster than 980 Ti SLI in most cases, draw 1/3 the power, and be cheaper. You might be better served by selling your two cards and moving up to a single 1080.

 

[Ecky]

Looked at some benches, it's really back and forth. Probably not worth your time and effort, unless you feel like it'd be nice to have a system that draws <350w under load.

 

[elbert]

First let me say I wouldn't suggest upgrading unless your overclocking. The 6800K is a lower clock and not a great improvement. Here is the compare and im unsure why Intel release the CPU at such a low clock rate. Overclocked tho you should get beyond anything the old 4820K would do.
http://www.anandtech.com/bench/product/1330?vs=1727

Also a heads up the 200 series with kabylake will have 24 lanes. Here is a compare between the 6700k and 6800k.
http://www.anandtech.com/bench/product/1543?vs=1727