Quad GPU Render rig - component requirements?

[BunnyToes]

Budget (including currency): ~$7000 USD

Country: USA

Games, programs or workloads that it will be used for: Cinema 4D, Octane

Other details (existing parts lists, whether any peripherals are needed, what you're upgrading from, when you're going to buy, what resolution and refresh rate you want to play at, etc): 

 

Wondering about this - if you have any experience in building a quad-GPU rig almost solely for rendering, would there be a bottleneck from using a Ryzen 3950x or 5950x instead of a Threadripper?  Would I also need a mobo with 4 PCIe x16 slots to get everything out of the cards?  Ideally I'd be looking at 4x RTX 3080's when they're back in stock next year.  If I don't need all of the PCI slots to be x16, what could I use instead of the one mobo that has 4 (the MSI MEG Godlike)?

 

[Radium_Angel]

43 minutes ago, BunnyToes said:

Cinema 4D, Octane

Do those programs support a 1 to 1 increase in rendering power from multiple GPUs?

[BunnyToes]

On 11/30/2020 at 3:17 PM, Radium_Angel said:

Do those programs support a 1 to 1 increase in rendering power from multiple GPUs?

Cinema 4D, doesn't really need GPU's, it's CPU-based modeling that feeds Octane.  But Octane, yes.

[BunnyToes]

On 11/30/2020 at 3:27 PM, zhnu said:

You're going to have a problem with thermals, apart from that Ryzen wouldn't bottleneck with those cards, the MSI MEG Godlike is the only one that I know of that has 4 slots that will atleats have 4 slots with 4X, that alone is a big no-no means if you need a spare you're going to get in trouble eventually, so I would go for Threadripper just because you have multiple motherboard choices.

I see, that makes sense.  Thermals though?  Planning on making this build open-air, and CPU cooling however I need to.

[BunnyToes]

On 11/30/2020 at 3:32 PM, zhnu said:

Another thing I didn't remember is power how are you going to power all 4 3080?

This looks like a server build not a regular workstation.

Not sure yet.