WS C621E SAGE has 7 PCIe 16x slots.
Yet the manual (
https://dlcdnets.asus.com/pub/ASUS/mb/Socket3647/WS_C621E_SAGE/Manual/E15242_WS_C621E_SAGE_UM_V5_WEB...) allows only 4 video cards in its largest configuration.
These 4 video cards are on SLI, however. We don't use SLI (scientific compute), but we would want to be able to use all 7 slots. We don't mind going from 16x to 8x (but not lower than 8x).
Is it doable? If not, why would this board have 7 slots?