Intel core i7 6800k vs 6850k for 1080 SLI

[joltx]

Hello people

I wondered if the 6800k would be enough for two 1080 in sli for gaming. The 6800k only has 28 PCIE lanes so is that a bottleneck? Or should I wait for ryzen and see what they have to offer...

[Droidbot]

Ryzen is in the works still, slated for a Late Feb - Early Mar release.

 

lack of PCI-e lanes will not bottleneck the cards - they can run 8x/8x without any bottlenecking whatsoever. 

 

[MeepLikesToBuildPc's]

10 minutes ago, RoccoRiu5960 said:

Hello people

I wondered if the 6800k would be enough for two 1080 in sli for gaming. The 6800k only has 28 PCIE lanes so is that a bottleneck? Or should I wait for ryzen and see what they have to offer...

Well, ideally you'd want both 1080's running at PCIe 3.0 X16. multiply 16 by 2, and you get 32. Because of the fact that the 6800K only has 28 PCIe lanes, theoretically that's a bottleneck.

 

My opinion on Ryzen: I doubt they're gonna offer a CPU that has more then 32 lanes and will pair well with 2 1080s

[MeepLikesToBuildPc's]

2 minutes ago, Droidbot said:

Ryzen is in the works still, slated for a Late Feb - Early Mar release.

 

lack of PCI-e lanes will not bottleneck the cards - they can run 8x/8x without any bottlenecking whatsoever. 

 

You sure about that? 1080s are high end cards, I would be surprised if they're not using the full X16

[rn8686]

2 minutes ago, MeepLikesToBuildPc's said:

You sure about that? 1080s are high end cards, I would be surprised if they're not using the full X16

Not a problem, cards can run at 8x 2.0 fine (OP is using 3.0). 

[Droidbot]

6 minutes ago, MeepLikesToBuildPc's said:

You sure about that? 1080s are high end cards, I would be surprised if they're not using the full X16

Puget Systems did a benchmark where they ran dual Titan XPs on 8/8 and 16/16.

 

Take a look at the results here

[Paradine Sage]

8x8 vs. 16x16 is a marginal difference that really doesn't justify the cost increase.

 

Where SLI could get to be an issue is if you are also using things like an M.2 drive (uses PCIe lanes) and so on.

 

Honestly a better reason to go for the 6850k is that it clocks better as a general rule. The 6800's are pretty much just low binned 6850's and tend to take a lot more voltage and cooling to produce the same OC's while also having a lower ceiling.

 

If you don't intend to push your chip past 4.2 GHz or so and don't actually need 40 PCIe lanes then the 6800k is probably the better buy for you, although I would wait for Ryzen to release (it's only a month or so away) and see what that looks like.

[HKZeroFive]

8 minutes ago, MeepLikesToBuildPc's said:

You sure about that? 1080s are high end cards, I would be surprised if they're not using the full X16

There's no card that I can recall of that fully saturates PCIe 3.0 x8. There won't be a difference between x8/x8 and x16/x16. The i7 6850K would ultimately be a waste of money over the i7 6800K.

 

Take a look at GamersNexus' article/video where they use a GTX 1080 to demonstrate this: http://www.gamersnexus.net/guides/2488-pci-e-3-x8-vs-x16-performance-impact-on-gpus

[rn8686]

What are you actually using your PC for OP? If exclusively for gaming, 7700K is faster and will be fine for you (or light editing/rendering). Only if you need the extra cores for rendering would I worry about X99. 

[Droidbot]

1 minute ago, rn8686 said:

What are you actually using your PC for OP? If exclusively for gaming, 7700K is faster and will be fine for you. Only if you need the extra cores for rendering would I worry about X99. 

rule of thumb with x99 -

if you don't know why you need the cores you don't need them

[SaladFingers]

In reality x8 vs x16 are like 1-2% apart in terms of performance, and that's only when running something very demanding. So you wouldn't be really bottle-necked. Also like others said, if you don't mind waiting a little bit maybe Rysen will bring better value. You could still do 2x8 lanes and have an extra 4 lanes for other stuff like Nvme drives.

[Droidbot]

1 minute ago, SaladFingers said:

 extra 4 lanes for other stuff like Nvme drives.

one drive. all 4 lanes will be used on one drive

[SaladFingers]

1 minute ago, Droidbot said:

one drive. all 4 lanes will be used on one drive

Yeah, I didn't imply he could use several at the same time, just that he could use those 4 lanes for other stuff - some of them being nvme drives. I'm sorry for the confusion

[Simon771]

It depends on workload that you put on those GPUs.

For most games, you won't notice any difference.

https://www.pugetsystems.com/labs/articles/Titan-X-Performance-PCI-E-3-0-x8-vs-x16-851/

 

Here are detailed results of x8/x8 vs x16/x8 vs x16/x16

In some cases x8 is acctually performing better than x16, and I just can't explain why is that so.

 

And are you sure, you don't want to wait 1 or 2 months more to see what AMD has to offer? Even if you are not interested in buying AMD, you can at least wait a bit more and see if Ryzen release will force Intel to lower prices.

I'm also looking to upgrade for i7 6800k, but I will wait for Ryzen release and then decide what to do.

[joltx]

4 hours ago, rn8686 said:

What are you actually using your PC for OP? If exclusively for gaming, 7700K is faster and will be fine for you (or light editing/rendering). Only if you need the extra cores for rendering would I worry about X99. 

I do quite a bit of rendering and editing of videos.