CPU or GPU ?

[John_Do]

Hello,

I don't know if it's the right place to discuss this subject but I try.

I have to buy additional hardware by the end of the year and I am considering 2 options :

- a additional render node with one Xeon E5, followed by a second one later
- or a couple of Titan X ( Pascal ), to use V-Ray RT GPU on production and with my 980
These two options are quite different, each with a specific workflow. But except the price of the CPU configuration, the main difference is the memory. Let's say all the scenes I work on fit in the GPU memory.

In regards of the slowndown in CPU progress, the exorbitant cost of modern CPU ( Xeon +16 cores ), and the convincing progress of GPU computing power, is it more interesting to invest in CPU or GPU ?


Two questions to make the right decision:

Does V-Ray have "out-of-core" features and can use CPU RAM to load textures and geometry that doesn't fit in VRAM ?

Is V-RAY RT GPU will support as many functions as CPU in near future on Modo ? ( https://docs.chaosgroup.com/display/...y#MODOTextures )



TL;DR

I mainly work on architectural and product visualization stills. Should I invest in a ( additional ) dual Xeon render node or a couple of Titan X to cut down my render times ?

Thank you

[pixelwerk]

Well, I went for the CPU-Version, since there are still too many GPU-rendering limitations, no matter what kind of engine you're using at the end.
Can't tell you how this will be in a year or two, but for now my renderfarm is still doing a great job, even though it's already three years old and three years back, GPU wasn't even less off an option.

With an eye at the factor "Bang for the Buck" i went for 6 x i7 3930K (6 cores) instead of an expensive multi CPU Xeon-System. Today it would be i7-6800K (6 cores/12 threads). You can easiliy overclock them to 3.8 Ghz without having to worry about cooling. They won't go beyond 80°C even when rendering for two month non-stop. Equip them with some cheap ASRock motherboard, enough RAM and a 128 GB SSD for your System and a 1 TB HDD for all project-related files and you're ready to go. All together each rendernode will be around € 700,- + an additional V-Ray standalone-license.

Distributed Rendering works absolutely perfect with V-Ray for High-Res stills and I'm using it daily for my product shots and Interiors.

[John_Do]

Thanks for your reply

Well, I'm already using DR with 1x3960X, 2xE5-2670 and 1x5960X ( my WS ). Despite this good amount of computing power, render times are too long because I do jewelry / watches stores, often with 20/30 IES lights, much glass pane and many small elements and it's really hard to compute the GI. IR map gives acceptables render times but quality is not convincing and artifacts are common. So I want to use bruteforce.

So a additonal render node is a good option ( with 2 E5 v4 ), I aim for 5000 to 6000 points on Cinebench. It's an heavy investment but I can't store 6 computer in my tiny office, and I save the RN licenses cost.

And yes, DR is really great on V-Ray, it works far better than the Modo native engine. Don't you have a NAS to manage your files ? Very useful when you have multiples machines

[pixelwerk]

I'm running two DS1515+ NAS from Synology here for file-exchange and as file-server.
It's always a tough calculation, and I've gone through mine over and over till i found what was right for me back then. At first i was also after a multi-CPU version, like my WS but at the end this solution was by far more expensive even though i would had to buy less V-Ray licenses and if you go for smaller 2HE 19" rackmount cases f.ex Chenbro RM24100-L they don't take that much space once stacked

[John_Do]

Yes ideally I would go for a 19" cabinet with cheap 6 cores nodes to have a efficient and scalable system...but it needs a specific room, these 40mm fans are way too loud to sit next to it.

[GidPDX]

Still might be worth it to have a 1080 or 1070 around to handle things like denoising and free up your CPUs a bit. GPU is by far faster with such things AFAIK.

For my day to day work and how small and relatively simple my scenes are I think I'll be trying the GPU route, and then when I hit bottle necks, sending off to a farm.

[pixelwerk]

Oh yes...far to loud...I went for 3HE racks and even they are loud..was glad that i was able to place them outside my office in the next room. Especially because of the heat they. Unable to stay in the same room with them during hot summer days.

[John_Do]

Still might be worth it to have a 1080 or 1070 around to handle things like denoising and free up your CPUs a bit. GPU is by far faster with such things AFAIK.

For my day to day work and how small and relatively simple my scenes are I think I'll be trying the GPU route, and then when I hit bottle necks, sending off to a farm.

I could but for the moment my 980 is enought to handle this kind of task, few seconds on 2K render, few minutes on 8K render.

I'm looking for numbers :

- 6 * 5820K = 6 * 1335 ( OC ) = 8010
- 2 * E5-2679v4 = 2 * 3025 = 6050

For roughly the same cost in hardware. The 6 RN are more powerful but cost an extra 1000 EUR in RN licenses. The dual xeon is less powerful ( but for a single machine it's a computing beast ), but cost less in license and is simpler to manage.



sources : http://cbscores.com , http://www.overclock.net/t/1431032/t...r15-cpu-scores

[John_Do]

Oh yes...far to loud...I went for 3HE racks and even they are loud..was glad that i was able to place them outside my office in the next room. Especially because of the heat they. Unable to stay in the same room with them during hot summer days.

Yep that's it...professional hardware need professional place ! On the other side it is great for winter haha

[GidPDX]

Sorry, somehow missed that you'd be keeping the 980.

Playing devils advocate- with the k series chip setup you would get more redundancy though if something should fail.

That said your over all power costs would be more yeah along with the license costs.

BTW- Where are you finding E5-2679v4 chips for sale? I can find only two areas selling it, and it's not listed on the ark site:

http://ark.intel.com/products/family...v4-Family#@All

[John_Do]

Yep redundancy is one advantage of distributing computing power across multiple machines. I'm thinking about it but the heavy logistics really doesn't attract me.

You can find these chips on eBay. There are no official way to buy this CPU because it's an OEM CPU, designed for some server manufacturer. Unlike his brothers the TDP is higher ( 200W against 145/160W ), so the frequency !