EVGA SR-2, with waterblocks.
The rendering per gpu is +16% faster than my old GTX580.
Same GPU as TiTAN, GK110, 7.1 billion transistors
7x GK110  = 49 billion transistors in one pc.
3 powersupplys.
Draw around 2600w +
24GB of ram for stability and speed.  home welded frame.
A separate big watercooled machine with 10x 40mmx40mm Peltier to hold the 2 x cpus at around 18c and 4300mhz   
The cooling systems hold one fat 80mm 4x120mm and a 80mm 3x120mm radiator.
4xrenderslaves with dual dual 56XX with total capacity of 96HT cores and 48GB ram.
 

Please do post some photos of this Monster!

Got 95% of the stuff, it is the biginning of the build,
the graphic cards and mobo is in Place in the chassi,
Also the cpus and waterblocks.  
Can post some pics on sunday.
Regards Robban

 
In my previous build, the underclocked and undervolted  2xGTX590 burnup from the heat under rendering so i
Moved the PSU`s for more GPU space.
The chassi will be a big rack version, ( mining style rack )
 
 
 
 

Impressive, Robban. I kind of expected more than +16% per GPU from the GTX780 compared to the GTX580 for rendering. I don't know which rendering software you're using. However, I was surprised when a quick look at Tom's Hardware showed that the GTX780 was slower than the GTX580 with the rendering software they used, except for Octane where it was about 29% faster.

Really like the place of GPUs, I'm mounting my custom horizontal case and I don't like the pipes of gtx strix above the SR-2 plate fan, so I can get cooler both GPU's and plate fan. Thanks for the idea.
Where will you mount PSUs? Above all or by the side?
Which is your CPUs temperature with the 4X120 radiator?
And you're lucky cause you can leave it open, I've got 3 cats and a dog, so... I can't!!!! 

The GTX 580 is doubt a Winner in most of cuda applications.
Really blending fast.
I buy old stuff so for me the 780 is a cheap upgrade, fits my wallet :-)
3GB standard, and for me 100% more Ram.
Future upgrade : 5 old TiTAN 6GB + my 2 gtx 780 strix give me 6GB.
 
Im going to mount the PSU`s behind the GTX if it fits.
But high up so the air flow from 4x120cooler runs under PSU and over SR-2.
 
 
Inside house,, no way !  we have a cat too and the noise is to much.
In a Little garden house on property :-)
 
SR-2 is still a killer when overclocking and 3ds max likes fast cpu´s
A Little welding on case/chassi next week to secure the GPU`s and mobo and build a new PSU holder.
 
The big 4x120 is only the cooler Before the watercooled thermal cooling maschine.
Im not finish with the build yet so
Maby in  1-2 months. 
 
i really want the cpus to go to max 18celsius when rendering.
It is easier to overclock when cpu is cooler. 
My new PSU link adapters.
for multiple PSU 
 
 
 
     

Robban, we're the same in the "I buy old stuff" for cheap upgrades for good performance. About using the Titan instead of the GTX780, I saw a thread on the Octane forum discussing that the GTX780 works fine, whereas the GM 200 Titan X (same gen) the IOMEM limitation of the 32bit SR-2 bios made it not run when populating all slots. It might be that it was due to Windows, and switching to Linux might have addressed the issue. I'm not sure. See the thread here: https://render.otoy.com/forum/viewtopic.php?f=40&t=43597&p=248528&hilit=notiusweb#p248528. BTW are those 780s you're using the 6GB version?

Where did your Get This Little Bad Boy?

I could use a few myself.

the gpu on old 780/titan is GK110
and they work fine.
got 2x asus 780 strix 6gb
Titan X is a newer model and to expensive fore me.

I tested gtx780 in 3ds max without superoptimize bios and 16% is really good.
render a short ~10sec scen and 780 is 2sec faster than 580.
did a series arion render benchmark and reach over 9000 points with my old gtx580/sr-2 overclocked.




Little Bad boys:
on ebay.
the seller :xyzhou2012.

Link Multiple add2PSU Dual Triple Power Supply Adapter Connector Relay Adapter

A easy and cheap way to make all psus start at same time.