Advice on building a new rig 3x or 4x GPU

[moriah]

Hi guys first post here,

We're planning on buying Octane to do part of our product and advertising animations, since it's a lot faster than Vray for certain things. We'll be using both, but primarily Octane.
Our render farm consists of 15 machines, but most of them are outdated, but it's a relatively well cooled place with 2 AC units.

We want to start with just 1 machine to see how it goes and it would be my workstation which isn't placed in the renderfarm room, but right next to me.

My current build is:
i7 3930K OC
Asus P9X79
32GB DDR3
EVGA GTX 780 3GB
Noctua cooler for CPU
600W PSU

From my research, since i'll have the workstation right next to me, the ideal amount of GPUs would be 3x 980 Ti's. My question is if i can ditch the 780 and the PSU, and just get 3x 980 Ti's and a Corsair AX1200 (from what i've seen 1200 is adviced for 3 980's, since the recommended PSU wattage for the entire system is around 990W). Not sure if this motherboard can support it. Or if i have to buy another motherboard, cpu and ram, what should i get for 3x GPU's? Or even 4 maybe?

Also in the future, what would you advice for a render machine? With AC unit on top of it. Let's say a 4x GPU machine, do i need a good CPU also? Or just a bare minimum will do? Also the motherboard.

Sorry for noobishness but i'm new to multiple GPU rigs

[bepeg4d]

Hi and welcome,
unfortunately there are different types of Asus P9X79, PRO, DELUXE, WS, LE and even an E WS, so, to better help the hw gurus in answering to you, it would be nice if you could be more detailed, because the PCI specifications are quite different from type to type.
About the render farm, roughly, if you put one recent GPU in each of them, you easily arrive to the 20 GPU limit per Master node, with two you can use half of them with one master and the other half with another master.
Is quite easy to add one or at least two recent GPUs on old systems (at least with a PSU upgrade only). Exceeding this is not so easy, probably you need to upgrade also the mb and other parts, and take care of the overheating.
An Octane net render node doesn't need fast CPU, but only a good network interface and good GPUs, since all the scene is prepared and managed by the master
You must have an Octane Render Standalone licence for each slave, while only the master must have a Standalone plus an integrated plugin licence if needed.
ciao beppe

[acc24ex]

if you can fit 3x 980ti in it, it should work, by the looks it seems that it can, only it will be tightly together, as I'm running 3x980ti on a work computer, it can be done with just more fans blowing directly at the gpus..
- the limit is 12 gpu total (so far), and you don't need a powerfull cpu, just the basic stuff will do for render farm

[moriah]

Here's a screen from Speccy of the motherboard specs.



And we don't plan to add GPU's to the current machines in the renderfarm, but instead we want to get a new single machine with 3-4 GPU's there just for Octane and Vray RT GPU.

Also, for my workstation, i imagine 3 GPU's under load make quite a bit of noise. Without going into watercooling, i assume the best way to reduce it would be to get a really nice case for isolating noise? What would you recommend?

Thanks!

[moriah]

After some more research, what do you guys think about this?

My Workstation Upgrade:
will maintain:
i7 3930K OC
Asus P9X79
32GB DDR3

upgrade:
Corsair Carbide Air 540
4x Noctua NF-P14 PWM Redux 1500rpm 140mm
Corsair AX1200i
3x Gigabyte GTX 980 Ti WF3 OC 6GB

And for a renderfarm machine:
Corsair AX1200i
3x Gigabyte GTX 980 Ti WF3 OC 6GB
ASUS X99-A
Intel i7 5820K
Kingston 8GB DDR4