delta5 :
btw, is it worth getting a m2 ssd for the OS over a normal sata ssd?
Yes, very much so.
I think the ideal config is the following.
BOOT: m.2 or fast SSD for boot. This drive will hold only the OS and a few critical items. It will not be hammered. It is not very likely to suddenly die. Having very fast system calls is also a good idea.
APPS: A fast SSD (or 2nd m.2 for the well heeled who have a system with a 2nd m.2 slot). This drive is designated for the early grave. You install your steam and other apps on this. You beat this drive until it dies.
BACKUP: a large (need not be fast) HD. This will have backups of your entire APPS: disk among other things. Thus when your over worked APPS disk dies, you pop in a new one and copy over the data.
Also on the x299 or 2011-v3 motherboards and CPUs. I think you'd need to go to a 7900x or 6850k to get 16 lanes to the CPU per PCI slot. But as of today video cards don't saturate a 8x 3.0 slot. The drop off on z270 and z370 boards when you add a 2nd video card is just a few % (~2) and this is just due to overhead from SLI. So there is no point in above 8x 3.0 except for future proofing (which never works) or adding a 3rd card some day.
Finally on your PSU, I think you should review this:
https://linustechtips.com/main/topic/631048-psu-tier-list-updated/
and get a tier one if you can.
I'm not sure 1000w is going to be enough unless it is a very high efficiency PSU.
A quick high-end sample build which sounds like it includes the stuff you were talking about. Dual 1080ti's etc
PCPartPicker part list /
Price breakdown by merchant
CPU: Intel - Core i7-8700K 3.7GHz 6-Core Processor ($414.89 @ B&H)
CPU Cooler: Noctua - NH-D15S 82.5 CFM CPU Cooler ($78.99 @ Newegg)
Motherboard: MSI - Z370 GODLIKE GAMING EATX LGA1151 Motherboard ($486.70 @ Newegg Marketplace)
Memory: Corsair - Vengeance LPX 32GB (4 x 8GB) DDR4-3200 Memory ($409.99 @ Amazon)
Storage: Samsung - 850 EVO-Series 250GB 2.5" Solid State Drive ($94.99 @ B&H)
Storage: Samsung - 960 EVO 250GB M.2-2280 Solid State Drive ($124.99 @ Amazon)
Storage: Western Digital - Green 4TB 3.5" 5900RPM Internal Hard Drive ($145.00 @ Newegg Marketplace)
Video Card: EVGA - GeForce GTX 1080 Ti 11GB FTW3 HYBRID GAMING Video Card (2-Way SLI) ($849.99 @ Amazon)
Video Card: EVGA - GeForce GTX 1080 Ti 11GB FTW3 HYBRID GAMING Video Card (2-Way SLI) ($849.99 @ Amazon)
Power Supply: SeaSonic - PRIME Titanium 1000W 80+ Titanium Certified Fully-Modular ATX Power Supply ($252.99 @ SuperBiiz)
The above says the system draw (with nothing else, no case fans, no USB devices, etc) is 829w. They assume that the video card is capable of 280w. But Tom's and other sites have measured the founders edition being capable of hitting 297w (call it 300 to be safe). Or a more likely max power of around 869... A PSU is not going to be very efficient above 80. % For a safe 20% cushion, a 870w use should have a PSU of around 1050w. So your 1000w, if it is not a very good one, would not be enough. If it is a very good one, it would be used a little on the high end. If you plan on attaching a bunch of other stuff, then it is not enough power.