New render farm builds - Dual CPU vs Single CPU

[joseph_perenia1]

I'm refreshing our render farm hardware and we're currently trying to decide between dual CPU vs single CPU builds. A good amount of our projects include Vray so I'm building around this.

I checked out the hardware requirements page and an old forum post, and it mentions that dual CPUs don't perform as well as single CPUs. Is that still the case? We're looking at the AMD EPYC CPUs for this purchase.

[Morbid Angel]

I would advise against buying epycs for rendering. Those machines are generally made for virtualization, to run multiple vms. If you are really thinking of high performance I just built two of these: AMD Ryzen threadripper 7980x, 64 core. This is not the top end cpu though, I think they have another variant 7995wx thats got 96 cores. Anyway, the performance on that cpu is insane. And it being a single cpu it does not suffer from some of the threading issues dual multi core cpus have. I would highly recommend you look into these.

[Joelaff]

We have found the 7995wx is amazing for rendering, and generally around the speed of 3.25 or so 7950x consumer level machines. Makes an excellent workstation for lighting and texturing.

But…

You could easily build six to ten 7950x machines for the cost of one 7995wx. Of course now there are 9950x which are even faster, and cost only a bit more than the 7950x setups. We have been using 9950x for the latest builds.

Unless you are limited by individual frame speed, many smaller machines render a lot faster than fewer faster machines. All the single threaded operations run much faster on the lower end chips. This is even more true on Epyc which are very slow for single threads.

Added benefit of the many smaller nodes is that when one node is having a problem you don’t have to immediately fix it because it’s a much smaller percentage of your render power. If you only have a few super power machines then when one goes down it’s a big deal. And they all periodically go down for various reasons— when you abuse these things 24/7. If not the machine itself, it’s the OS, or the UPS, or the network port, etc.

Also, the consumer grade stuff is cheap enough you can have spare power supply on hand at all times, and if you need replacement parts you can get them off amazon in a day or two.

Not to mention the noise server hardware makes…

[glorybound]

In my opinion, unless you're creating animations, even consumer-grade machines do just fine. An hour, with desoiser at about .4, anything I throw at it works just fine and is nice and clean. I can render on my GPU, and it'll finish in an hour, and on the CPU, I can cancel after about an hour. However, if an hour is too long then maybe commercial hardware is what you need.