Does anyone know of a decent dual LGA2011 board that fits into EATX, has 6 PCI-E 16x and has the full 16 DIMM slots? TYAN S7053WGM4NR would be an option - although might have to get a bigger case - if it had 6 x physical PCIx16, but for some idiotic reason four of the slots are physical 8x (cost savings on a $600 MB, really?).
It's pretty rare (outside that Asus board you mentioned) since most people who need PCIe x16 are driving GPGPUs and those are dual-slot designs. EATX can't normally handle that (outside of watercooling, but that's pretty rare).
EDIT: Can anything actually use the additional bandwidth of a PCIe 3.0 x16 slot right now? You could go something crazy like the X9DRX+-F (10 x8 slots!)
Two PSUs is kind of annoying - I'm running a pair of Zalman ZM1000-HPs in my curent machine - but I don't know of any >2kw solution unitary solution that fits in an ATX form factor, has appropriate cabling and doesn't come from a really dodgy manufacturer. The STH10 actually supports quad PSUs, which I find amusing (maybe one day AMD will fix their driver crap and I can have that 12-GPU sextuple 6990/7990 setup; EK make the single-slot waterblocks, but anything over 8 GPUs is still impractical for AMD cards).
Why don't you just go rackmount at this point?
Might as well put another SSD in there to populate all SATA3 ports, 3 x Samsung 830 in RAID-0 for 768 GB sounds good (although practically the southbridge will probably saturate).
Can you give up a PCIe slot for something from FusionIO?
My network configuration is beginning to flake out, so in lieu of actually trying to figure out what's wrong, I'm going to go the easy way, and replace all the network bits (well, almost, the 100 Mbit switch will likely go to the living room). I'm pretty sure it's due to the age of all the bits (almost 6 years for the oldest bit).
I have a WNDR3700v1 running an IPv6-oriented OpenWRT build that's pretty solid. Apple's Airport Extreme is very good but it's expensive for what you get.