Right now just (3) 1080ti.
One 1080ti will be on motherboard. The other 2 on riser.
GPU will need at least 3 pci-e cable. Riser will need 2 more. Total of 5. Even if that enough for now it may not be when 1 more GPU go in.
That why I'm asking about molex or sata.
If I right those PSU come with PCIe 8pin (6+2), 2x 6pin, the rest 1x8 pin (6+2) and 2x6pin.
if you plug 1 more GPU, the 8 pin (6+2) would be powering your GPU, The Riser using 6pin.