I know what you're gonna say..."that's what 'X' boards are for", but wait; Yes, my understanding of the engineering is a little wanting on the matter but if most boards support 1 x16 slot and a bevy of x8 and x1 pcie slots could not a maker just put a total of two pcie slots both x16? Also, the reason I ask is I just p/u a GTX 970 which I am very happy with but I also ordered a Korean 2K monitor and plan to overclock it a bit. I'd like to run 2K @ >60hrz and I understand that my one GTX 970 will not be up to the task so maybe in a few month...(xmas) I'll get another and SLI them. But then I remembered that they'll run @ 8x so now I'm like...does that make any sense or should I just stick with one card and deal with the low frame rates of drop back to 1080p...uhg, first world probs!
Simply put you don't really need x16 bandwidth for a 2nd GPU, even x4 which AMD lets you run a second GPU on only cuts performance by maybe 10%
You should also just save your money for next year, but up a 4k display when you can, then get a 4k capable GPU when they come out next year, with HBM2
There are Z boards with plx chips that do support more lanes but are expensive.Its about Cpus not having enough lanes not motherboards.
Second what @ignx said, the Z-series motherboards have cpus with a maximum of only 16-pci express lanes while X-series motherboards have cpus that go upward of 40 with the i7-5930k/5960x. but skylake has additional 4 lanes for peripherals. AMD does it similarly with their A-series and FX Cpu. They are segmenting their market it easier to sell products that way among other reasons.
Because it is expensive to implement and largely unnecessary. People who need more than 20 pcie 3.0 lanes (since skylake anyway) shouldn't be on the mainstream platform. It is also another insensitive to make people want to go with the more expensive product.
X4 3.0 is the same as X8 2.0. You will see no performance change on either.
so then is it worth it to sli on z97?
Z97 is totally fine for SLI. It is X8/X8 3.0 Which is the same as X16/X16 2.0.
You'll see no performance loss. Whether SLI/Crossfire in general is the best option is debatable but nothing about the platform will limit you.
Lol.
8x PCI-E 3.0 has MORE THAN enough bandwidth,
You could, but you should really just save your money, get a nice 4k display and later on next year get a solid single GPU with HBM2, in the mean time you should be able to push most games pretty well at 4k low-medium, and any games you can't well just run them at 1440p