Help choosing mobo for 2x/3x GTX 980's with PCI-E SSD or M.2

[Sd4Insanity]

Hello everyone! I'm contemplating a massive upgrade to my system, but I need some pro-tier advice regarding available lanes per chipset and socket type. Ideally, I'd like to run at least 2 EVGA GTX 980's in SLI (potentially 3 in the future) along with a Samsung SM951 or SM950 Pro 512GB SSD. I'm aiming for extremely fast startup/shutdown times, transer rates, and 4k gaming. As a result, I've been considering the I7-4790k, the I7-5930K (i believe thats the one) and the I7-6700k, paired with an Asus or EVGA motherboard (though I'm open to suggestions for good motherboards that are cost-effective).

My question is this: Is it possible to get 2.5Gps read/1.5 Gps write speeds on the Z97 or X99 chipsets while running dual GPUs at x16 SLI?
Is x16 even necessary to run SLI at 4k, 60hz, High to Ultra settings?
If so, what motherboard will allow dual GPUS in SLI with that speed from the PCIe SSD? Is the x16 necessary for all 3 components, or will i be alright running the GPUs at x16 or x8 and the PCIe SSd at x16 or x8???

If not, then I'll pick up an I7-6700k and the question changes yet again: What motherboard with the z170 chipset will support my PCIe/SLI configuration at the highest bandwidth rates? I'm trying to go big, and I've already got everything ready except the CPU/Mobo/DDR4 Ram. I'd rather not have to spend more than $600 for the cpu/mobo together.

Please help me!! I've been researching this for awhile, and it seems that an I7-4790k is a reasonable option, but I'm worried I'll be maxing it out the second I get it, and that it won't be able to handle a PCIe SSd, let alone a 3rd GPU. I sincerely appreciate the insight, and thank you for taking the time to assist me with such a detailed question.

 

[Aleszandro143]

Hey Sd4Insanity,
For your first question, yes it is possible to reach 2.5Gb/s and 1.5 Gb/s speeds on X99 chipsets with 2x GPUs. However in Z97, its 8x 8x not 16x 16x like in X99, and in X99 it is only 16x 16x with a 5930K or a 5960X (or a Xeon) because of the 40 lanes otherwise with a 5820K it is 8x 8x. 16x will make it better, not by much but it makes the SLI more reliable with a large transfer bus compared to others. Both motherboards will supply the speeds but I suggest going for a X99 system, however this would go over your budget of 600$ for a CPU and Mobo, unless you go 5820K, and with a 5820K you are limited to 2 way SLI. The ssd will run at 4x not 8x or 16x. It is the maximum speed for the SSDs right now.

But do not worry, if you get a Skylake build, then you can get 8x 8x, like a 5820K with x4 on the SSD and you might be able to squeeze a third GPU depending on the board. However it is unlikely like a X99. I would suggest preferebly to go X99 with a 5930K but a 5820K will also do.
Remember, 5820K = 2 Way SLI max with SSD
5930K or 5960X = 4Way SLI max with SSD

I recommend going with X99 Deluxe usb 3.1, with a 5930K. 16GB RAM and the 2-4 GTX 980s. Also while doing this you will have a dedicated sot to have a M.2 x4 slot for your SSD.