[SOLVED] Two RTX 2070s vs one RTX 2080 for 3D rendering (The program I am using does not use sLi)

[xxscienceboyxx]

I was thinking if two RTX 2070s could surpass a RTX 2080 in rendering performance. Would it?
And I know that the RTX 2070 does not support sLi. But, Blender's cycles rendering engine can use multi GPU without needing sLi.

Thanks!

 

[Darkbreeze]

Not that I doubt you, at all, but do you have any textual proof of that, because I'm actually working on another thread for a game developer who wants to use a dual 2070 configuration using blender, among other programs, and I couldn't find any evidence that it did support that.

As for the performance, I guess it would really depend on HOW it uses them, and honestly the cost of two 2070's plus the cost of a PSU capable enough of powering two 2070's, which would need to be at least a 1000w unit and a very good one, not some cheap low quality model even if it's from a good brand, based on the 500w per card recommendation, would probably make it not worth it even versus a 2080 TI which you could get for about 1000 dollars for the EVGA Black model. Which in fact is probably what I'm going to recommend to him as well.

 

[captaincharisma]

if the program you use does not support SLI then why waste the cash on 2 GPU's? lol. the only way to combine the power of the 2 cards would be with SLI

 

[Darkbreeze]

He's saying that Blender can benefit from multiple cards without SLI. I'm skeptical, and would like to see some evidence of this, because obviously the 2070 cards don't support the SLI/NVLink configurations.

FWIW, he didn't say Blender doesn't support SLI. It's the CARD that doesn't.

 

[nuttynut]

Not that I doubt you, at all, but do you have any textual proof of that, because I'm actually working on another thread for a game developer who wants to use a dual 2070 configuration using blender, among other programs, and I couldn't find any evidence that it did support that.

As for the performance, I guess it would really depend on HOW it uses them, and honestly the cost of two 2070's plus the cost of a PSU capable enough of powering two 2070's, which would need to be at least a 1000w unit and a very good one, not some cheap low quality model even if it's from a good brand, based on the 500w per card recommendation, would probably make it not worth it even versus a 2080 TI which you could get for about 1000 dollars for the EVGA Black model. Which in fact is probably what I'm going to recommend to him as well.

Blender Cycles is an offline renderer and uses CUDA or OpenCL, not OpenGL. SLI would actually hurt performance as a non-SLI config supposedly has 100% scaling with multiple GPUs. Maybe SLI would improve viewport performance, but that's not really a consideration.

And I would beg to differ on the 1000W PSU requirement. The 500W recommendation is for a system, not to power the card itself. I would calculate the total system power draw plus a 20% margin and that should be sufficient for an 80+-rated unit to operate efficiently. You can increase the wattage from there to allow the PSU to run in silent mode, but that probably won't require 1000W.

Another thing to point out is that as far as I know, Blender does not support RTX. Maybe they'll get around to it in a year or so. Also, CUDA support may not be fully implemented. It's almost certainly lacking in the latest production build.

 

[nuttynut]

if the program you use does not support SLI then why waste the cash on 2 GPU's? lol. the only way to combine the power of the 2 cards would be with SLI

For a game engine, yes, but not in this case. Think of it like bitcoin mining where there are big mining rigs with several GPUs.

 

[nuttynut]

To actually answer your question, while there are no RTX 2070 benchmarks for Blender, it gets a score of 210 from OctaneBenchmark, and the RTX 2080 gets 226. A 2-card setup should crush the 2080. https://www.cgdirector.com/octanebench-benchmark-results/

 

[Darkbreeze]

The PSU recommendation for SLI 2080's is 900w. They only have a 50w difference for a single card between the 2080 and 2070. In SLI, both cards are cycling and the load is balanced between cards. Two cards NOT in SLI, uses more power than two cards IN SLI. So yes, even though the recommendation is for a system, I'd still want to see a minimum, with a very good power supply, of 850w, and 1000w would be a lot better given that power supply peak output diminishes over time due to capacitor degradation AND because we KNOW that the power consumption seen in recommendations at the time of most reviews, does not accurately reflect the same power consumption of the same card down the road after changes to drivers and after the card has some miles on it.

A brand new graphics card pulling 250w when new will likely increase that later on to deliver the same amount of work.

 

[nuttynut]

Good to know.

 

[xxscienceboyxx]

I'll be buying used GPUs from ebay, so the prices might be cheaper.
I found some threads on other websites about if Blender multi GPU without sli works: https://blender.stackexchange.com/questions/5228/how-will-multiple-gpus-improve-cycles-rendering-performance https://blenderartists.org/t/two-gpu-with-no-sli/679607 https://blenderartists.org/t/multi-graphics-card-support-without-sli-utilizing-directx-12/699408

 

[Darkbreeze]

There has to be some overhead in the need to switch from GPU to GPU, so I'd still think that one more powerful card would be a better choice, not to mention the fact that unless you get some kind of fanstastic deal, a single card will still be cheaper especially if you factor in the need for a very large power supply. But obviously, it's your money, and you can spend it however you want.

Personally, I wouldn't buy a graphics card from ebay even if it meant having to use integrated graphics for a while. There are WAY too many abused cards on there, and fakes. The majority of cards for sale on Ebay right now were mining cards that were either run 24/7 for months and months on end, and rode hard, or have had their BIOS altered for mining. Sometimes you can get them back to the original gaming firmware, but not always, and usually any card that was altered has been used like a downtown girl anyhow and isn't worth any investment, much less what they are asking for them. Some get lucky, most do not. Obviously using a reputable seller raises the chances of success, but then again, there are a growing number of hacked Ebay accounts selling crap as well.