Done my research, now I need a review. 20 GPU cracking cluster.

[Betawave]

Hi all!

First off...  yes.  This is a serious post.

I won't bore you with the details, but essentially I've been tasked by my team at work to create a password cracking solution and have a budget of up to $30,000.  I've looked into using PCIE extenders, but those seem to be disliked by the community (price/return thing I guess).  Anyways, I did a bit of research and came up with a solution that I think would fit our needs.  It consists of five hosts with four GTX 980 TIs each.  The five hosts would be clustered to distribute the load.

I'd like to get some opinions from the crowd here since you are all pretty much the experts when it comes to hardware builds for this kind of thing.  Below is the config.  Feel free to rip it apart, and if you have any concerns, PLEASE post some details as to why.  

Each host will be identical, and contain the components below.  They will be located in a datacenter with the front facing a cold aisle:

Component     Quantity    Description
Case          1           Xigmatek Elysium CCC-HSA0DS-U01
PSU           2           Corsair HXi HX120i
Motherboard   1           MSI Gaming X99S Gaming 9 ACK
CPU           1           Intel Core i7-5930K
Memory        1           G.Skill Ripjaws 4 DDR4 2133 64GB (8x8GB)
GPU           4           Gigabyte GeForce GTX 980 Ti GV-N98TG1
SSD           3           Mushkin Enhanced Reactor 1TB SATA III
CPU Cooler    1           Zalman CNPS9900MAX-B

I'd really appreciate any feedback you all can offer.  If you are especially helpful, I'll be sure to put a badge on one of the boxes with your username on it.

Paging epixoip.

Just going to chime in with what everyone else has already said.. buy a Sagitta system if you have the budget...the markup is reasonable.  You can build a system for less, but you'll waste a ton of time researching and then getting it right.

I didn't have the luxury of a big budget and just recently built my own rig that is very similar in spec to what you're proposing (though I have a lot more disk storage).  Now that I've lived with it a while, I'm already convinced it's vastly underpowered for the type of research I'm doing, but your mileage may vary depending on what you do with the box(es).  I'm running 4x GTX970 (best bang for the buck) and that's just not enough.  I'm now debating how I can get more horsepower without breaking the bank.