how many gpus does your rig have? If it's more then 4 then go with server cases if 3 or less (like me) go with fractal define XL R2. This is HUGE pc case. It can easily hold 3 gpus attached directly to motherboard. The case comes with 3 fans and most importantly it has a removable air filters. The case also has manual fan speed controller which you can adjust depending on your room temperature. Also, the case has noise isolated walls, so it runs very quite. One thing to consider is the GPU temperature. You WILL have higher temp if you use closed cases. In overall this is great closed rig option if open rig is not suitable.
Thermaltake V34 or V35, can add a couple of Delta 120x38 or 140x38 fans to the front just by unscrewing the HD cages (use the floppy drive mount cage to mount a drive).
Can run *4* GPUs in this case on a motherboard like Phil's favorite Biostar or that AM4 board he posted earlier without having to mod the case at all (it's designed to handle 4 dual-width cards).
Very nice case for the relatively low price.
IMO though it's a lot better to go with open rigs, as they're a lot easier to keep cool - even for non-blower builds like I use and Phil generally prefers.
