bledha: You mentioned a thin PCI riser is necessary. Currently the motherboard is located on the left side. Is it possible to flip the back panel and have the motherboard on the right side? This way you can use a shorter riser cable. The only thing i can see being an issue is the PCI bracket on the outside.
That is likely an ill advised undertaking, the bottom panel looks like it could be unscrewed from the cubes and be flipped, but the back panel (independently) would also need to be flipped. However this presents major issues:
1. The cutouts for I/O and GPU I/O are not centered (see images), so you would need custom height motherboard mounts to reach the appropriate height or your motherboard will sag. I guess you could just stick junk underneath it....
2. Doing number 1 would then force your board closer to the top panel of the case, cutting clearance quite a bit for the CPU cooler.
3. The GPU I/O cutout is raised with a vent underneath for area to mount SSDs and some ventilation. If you flipped it, your area to mount the SSDs goes away and you force your GPU (now fans down) to the floor of the case, with its fans not breathing any air at all.
4. Not to mention the fact that flipping the bottom of the case would misalign all the appropriate mounting locations.
For the record, I am not sure (as I have
not tested it that a thin PCIe riser is
necessary. The area just seems very thin, and I am sure you can squeeze anything in there but the thicker ones - especially with the nuts from a mounting system like the Noctua NH L9i (which many folks use with SFF cases) will be very cramped and possibly pressed together quite firmly. A little more space should have been reserved for this in design. However, it is possible (as seen in
@amitoza's build with the C1, search the thread) to get a thick riser under a board as he built with a Lian Li one. The concern is more for interference from CPU cooler mounting hardware on the underside.
@fminus, if this is the config you're looking for, and it is a good one, just go with the S4.