Question Will I benefit from using 1070 and 1080 card simultaneously using CUDA for Cycles (Blender) rendering?

[MeshVoid]

Hello sexy people!

As the GPU market being updated with new models old GPUs become more affordable.

Will I get rendering speed increase (or any other benefits) by buying Nvidia 1080 8 gb ram and plucking in into a PC with the following specs:

Nvidia 1070 8 gb Vram
Motherboard: GA-Z77-DS3H (PCI Express 3.0 slots one is x16 and other one is x4)
CPU: I7-3770 3.4 ghz
RAM: 32 gb ddr3 1600

This Frankestein PC build is used as my workstation and is used mainly for rendering and modelling/texturing/animation purposes.


So the idea is to pluck 1080 into PCI3.0x16 slot and 1070 into PCI3.0x4 slot(I believe it will make 1070 slightly slower for real-time applications?) and use them for rendering purposes in Cycles. (No dual SLI GPU system, just two different videocards)

What are the pros and cons of such build? Will I get better rendering speed or will the other card negate the effect? What should be taken into consideration if you had the similar build?

Note. Motherboard does not support SLI it's actually a CrossFireX motherboard. But I believe this shouldn't be an issue for 3d software?


Thank you in advance!

 

[Satan-IR]

Not really experinced in rendering but as far as I know yes I think you can.

Blender works better with multiple cards (many places I've seen suggesting works better with no SLI), but how much VRAM your render engine uses will be determined by the card with smaller VRAM size, no problem if the same.

If the scene you want to render have very large textures or needs to use more RAM than what is available on the graphics cards, the scene will fail and not render, and the number of cards doesn't have any impact on this.

The card connected to the monitor would need to use some of its resources to deal with outputing a picture so I guess connect to 1070 and let the 1080 just render away.

You didn't mention your PSU make and model. You'd need a pretty decent PSU to run a 1070 and a 1080 under load. I'd say at least a good quality 850W unit.

Also there would be a lot of heat when those two cards are under load. Case needs proper ventilation.

That CPU is an i7 but some generations old and might be a limiting factor for two big cards.

 

[MeshVoid]

I don't remember the brand of PSU but it's definitely 850 watts and should be okay with two GPUs, if it won't I'd buy a new one I guess for this purpose. Indeed that CPU and motherboard is very old and needs replacement and I'm quite broke atm, so I'm thinking is it wiser to upgrade CPU and motherboard at this stage or pluck in second GPU and get things done faster right here, right now and then later down the line consider a whole new rig with completely new CPU, motherboard, memory and then eventually videocards?

Hmm. Regarding bottle neck situation. I've run the stats on bottleneck calculator of pc-builds.com/calculator and it gave me 17% of bottleneck with my current build with a single 1070. Is that a correct assumption, can it be trusted?

Does that mean I'm under-utilizing 17% of my current videocard's capabilities? To be honest even my specs are enough for my scenes that I'm working on currently, lag is only noticeable with very heavy textures and geometry, that you normally avoid working with for scene optimization purposes.

When I choose two 1080 cards for the same cpu model (It's not letting me choose two different gpus) this online calculator is telling me that the bottleneck would equate to around 50%! Is this correct or it will only affect real-time rendering and stuff like games? Can this info be neglected or does it affect absolutely everything?

To be honest, I don't care about gaming performance at all, as I don't play games, Mostly I render animation, motion graphics and make 3d assets and characters. And also I don't deal with realtime rendering too much, even with game-engines that I currently work in (Unreal, Godot) the performance is great and I'm okay with it, but I'd really want to be able to render frames in my 3d scenes faster.

So the question is - will those two GPUs running simultaneously in my outdated motherboard be an unbearable load for my CPU and will cause issues that I'm not aware of? If it is wiser to upgrade CPU and motherboard at this point, squeeze more from current GPU I have and buy newer GPU later? Or could I buy more powerful CPU for the same socket currently and go with two GPUs 1080 and 1070?

 

[MeshVoid]

I've made my little research and read through the articles and multiple computer graphics enthusiasts personal experience with the issue. I might be wrong, but it seems that the speed of gpu rendering (non-realtime rendering) with 2 GPUs will get indeed doubled (users claim that Cycles render indeed is doubled, as each GPU is rendering a square tile of a single frame upon rendering) and cpu bottleneck shouldn't be that huge of a deal as it affects only heavy realtime cpu+gpu processes (viewport performance will stay the same as it was, which is decent as of now). So I guess in my case the solution to buy a GPU and double render speed right here and now is more logical rather than buying a good cpu with a motherboard for the same amount of money and deal with relatively same render times. I guess if I did use my computer for gaming and real-time simulations the latter would be the most obvious choice. Please correct me if I am wrong here.

 

[Satan-IR]

The PSU exact make and model really matters. A good quality 500-550W PSU would be OK with just a 1070. Adding a 1080 to that is a horse of a different color. You really need a good quality unit. The most important part of any build is the PSU, performance and longevity of all parts directly depends on the PSU build quality to provide components with 'clean', constant power.

How old is yours? Open case and check the sticker/label on the PSU to make sure.

As those bottleneck calculators go they are mainly garbage and I don't think their algorithms are optimized (if you can call them optimized in the general sense of the word) for rendering using CUDA and are mainly focused on gaming. I'd say deisregard anything a bottleneck calculator will say for your special case/usage.

Rendering time will be decreased significantly as apparently Cycles and Blender give each discrete GPU it's own workload or tiles and it makes sense; two GPUs working on different parts of a scene at the same time rather than one single GPU doing all the work.

The decision is yours to get new MOBO/CPU/DDR4 RAM as foundations of a new architecture and then add another GPU to the mix later on. Or invest in a new GPU to make renders happen faster (which literally means more money faster!). However, how much a 3770 at 3.4Ghz would (if at all) hinder two GPUs working on the render tiles is something you have to ask people with extensive day to day hands on experience in rendering with Blender and Cycles.

EDIT: You must have posted #4 as I was typing. I personalyl would get the 2nd GPU if that really means renders with finish in half the time. P.S. Again, don't take the importance of the PSU lightly. Your budget might be tight but when it comes to PSUs buying god quality units really matters and pays off (which naturally are a bit more expensive).

 

[MeshVoid]

Thank you for your reply! I'll be buying the gpu for now. Regarding the PSU. I've opened my case and actually found out that it's not a 850watt PSU. It's an FSP Epsilon 85plus 800 watt PSU. Will 800 watts would be enough to feed two GPUs enough power? If this PSU is crap which would be the best option value for money wise?

 

[PC Tailor]

The FSP Epsilon series aren't actually bad, they're maybe not the best of the FSP line - but I'd be more concerned about it's age that anything. How old is the PSU?

I'd want to go higher end of a PSU if running 2 GPUs.

Much better end PSUs could include:

• Antec HCP
• Corsair AXi / HX / RM / TX-M
• Seasonic Prime / Focus Plus Platinum / Platinum (xp/xp2/xp3) / Focus Gold / Focus Plus Gold / X
• Bitfenix Formula Gold

That's just a selection, but obviously depends on the budget.

 

[Satan-IR]

PC Tailor said it and I couldn't have said it better. Your FSP is a few years old and I think has two 12V rails each rated at 20 amps. That's 240W on each and should work for the GPUs on paper.

Then again I'd rather have a single 12V rail with around 70 amps for those two cards and the rest as high quality 850W units tend to have that amperage.

I would also, like PC Tailor said, suggest a better quality unit, among those he listed.

You're not going to game and not sure whether you can set the loads on the GPUs while doing render computations, therefore, not sure whether you can ultimately set power usage or not. So if those two (1070 + 1080) are going to work at max I would want at least a 750W PSU.

For a some extra headroom and because PSUs lose some of their capacity over time, also to enable you to use the same unit if in a year or two you upgrade the system and get a CPU with higher TDP, I'd say get a good quality 850W. You can't go wrong with a 850W Seasonic or a Corsair RMx 850.

I say good quality because for example some of high quality 750W units can go as high as 800W for a few hours a day and won't hurt themselves or your components. Not saying you should do that but rather that they can handle a little extra pressure becaues of better design and components and not blow up and fry other components in the PC. But a low quality one, running for long periods under high load would start having trouble even at 90% load which in theory it should be able to handle.

As for best value it depends on where you are and the units and their prices available to you. You can wait for other members' posts on what PSU to get for best value.

 

[MeshVoid]

Thank you very much for your replies, now I have something to think about!

Ok, I just ordered GPU and it will arrive soon and I'l start running render tests. What about these PSUs as an option:

TwinMOS Xpower 900 900W
GameMax GM-1350 1350W
AeroCool KCAS PLUS 800W 800W
AeroCool VX-750 750W


They have very good prices in the stores near me. To be honest I don't know a thing about PSUs and how to check their quality. I guess my preference would be noise level and number of watt output.

 

[PC Tailor]

The top 2 I have never heard of, so I suspect should something go wrong they could burn your house down.

The only aerocool psu I have any recall of being good quality this year is the Aerocool Project 7.

Stay away from cheap PSU, they are cheap because the skrimp on the most important elements. Don't get me wrong, I'm sure they will run the system, but there are big risks and stability is not guaranteed.

 

[Satan-IR]

As PC Tailor said, you should avoid cheap units. He paints quite a picture and no there's no exaggeration there, low quality PSU can and actually have caused fires.

Stay away from cheap PSU, they are cheap because the skrimp on the most important elements.

Exactly, the reason they're cheap is that they lower production costs and they do that by coming up with cheaper design and cheap implementation that consists of cutting costs on all main components.

Mainly cheap transformers, capacitors, and rectifiers and lack important protection-related circuits and components. If you look inside a decent PSU you'd find variety of Japanese or Taiwanese electrolyic or polymer capacitors that are rated to run even at 105 degrees Celsius.

In cheap ones there are second/third rate caps that are rated at 45 for example. Your PSU can get hot under heavy load. Temps rise over 45 and after a while the capacitor blows. If you're lucky and the design is half-good the damage is contained there. If it's a cheap design (which most probably is otherwise that capacitor wouldn't be in there in the first place) you have a fire hazard in your case/home.

The prices might be tempting but you should avoid cheap, low-quality and practically unknown PSUs like the plague! The least that can go wrong is if they fail sooner than expected (and many low quality one do), wihtout protections in place, and you're lucky and there's no fire, your other components would be toast. How much would you lose if your graphics cards go up in smoke? Spend a fraction of that on a good PSU.

I'd check around for prieces of PSUs from the makes/series PC Tailor listed in post #7.

 

[PC Tailor]

I guess my preference would be noise level and number of watt output.

Also just be wary that the watt output is not exactly what is delivered, it is your 12V rail that deliver power to your main components, not the whole wattage output.

 

[MeshVoid]

Hello everyone! Thank you so much for your help! I bought the card ran multiple tests, works fine, two video-cards do actually double the speed of rendering with GPU renderers. If anyone is interested - Blender's Cycles benchmark BMW scene renders almost twice faster with 2 gpu's compared to just one 1080 on board! Which is a super satisfying result and I plan on building a more powerful rig in future with a decent mother board that would support 4 GPUs or so. As for PSU I will most definitely switch my Epsilon, It's been a while for it to work, it was actually a used PSU unit I bought off-hand with the case, motherboard and cpu almost a year ago, so I am more than sure that it is not safe to have it in my PC. I became quite concerned after reading horror stories everywhere. And It also became quite noisy, and I think it's turning into shit really, probably will buy new Cougar CMX850 850w this week, according to ratings it's a decent enough PSU, not a fancy tier one PSu but should do the job, I guess? And the prices are probably one of the lowest around me.

 

[PC Tailor]

I will admit I don't know about the Cougar CMX. I know some of Cougars other PSUs vary from good to not so good.

I would personally say the best way for you to make a decision at this point would be to look at something like this:

PSU Hierarchy (Dec. 2025) - Power Supply Unit List

Here is the ultimate list-based hierarchy of all power supply units. We've ranked them in 8 different tiers so you can easily find out if your PSU is good!

www.gamingscan.com

Then stick to tier 3 and up my friend, as your location and what is available at a fair price is obviously different to mine. However tier 3 and up should serve you well.

It may also be apt speaking to someone with more experience with the Cougar lines. I won't beat around the Bush, and say my knowledge of them is very limited.

 

[Satan-IR]

I'm glad you're happy with the results of getting two GPUs and using them to achieve higher render speeds saving precious time.

As said before by PC Tailor and myself you need a good quality PSU especially more so now that you're running two powerful GPUs at the same time when rendering.

Again I have to agree with PC Tailor and say don't get a low quality or mediocre PSU. It'd be too late when the PSU blows and takes your graphics cards and/or motherboard and other components with it to realize that the PSU is the most important part. The longevity and proper performance of all components depends on the PSU.

Is the PSU you mentioned the 850W on this page by any chance?

 

[MeshVoid]

I'm glad you're happy with the results of getting two GPUs and using them to achieve higher render speeds saving precious time.

As said before by PC Tailor and myself you need a good quality PSU especially more so now that you're running two powerful GPUs at the same time when rendering.

Again I have to agree with PC Tailor and say don't get a low quality or mediocre PSU. It'd be too late when the PSU blows and takes your graphics cards and/or motherboard and other components with it to realize that the PSU is the most important part. The longevity and proper performance of all components depends on the PSU.

Is the PSU you mentioned the 850W on this page by any chance?

Yeah, it's the one. And here's some reviews of it: https://www.techpowerup.com/reviews/Cougar/CMX_850W/ . I'd be glad to buy a fancier PSU, but I'm budget tight as of now =((, I'll do that in a year or so when I'll start assembling something more powerful with better cpu and latest GPUs. If I'm making a huge mistake buying this one please tell me =)).

 

[PC Tailor]

I don't think this is a huge mistake, however I'd be a bit worried because that review dates back to 2013, I'm not sure if Cougar have revamped that line any more since then.

I know the GSX series is decent enough.

Only concern with that in regards to competing suppliers is that the ripple suppression seems to be a let down, which is one factor that can lead to component damage, as its effectively how well it manages the fluctuations from AC to DC.

And the particular unit as per the review failed ATX spec on ripple suppression when the PSU became slightly overloaded - even if it was only on a 5V rail - which in reality means it conforms to ATX spec on your 12V rail which is what powers your major components.

But again, it does come down to what's your budget and what's available to you, I don't want to be a negative on any suggestions, but the last thing I would want to do is give a false sense of security. There are far worse brands than cougar put it that way!

 

[PC Tailor]

Another good way of seeing is checking the warranty, anything less than 3 years in PSU world is trash. Anything less than 5 is questionable in my opinion.

All I would say, is if you CAN pay to hit tier 3 and above on the list I posted, it'll pay for itself in the long run! Again, making comments on what I DO know in this matter, again, my experience with Cougar is limited.

 

[MeshVoid]

I bought a bit more expensive FSP Hydro G 850 w it has 5 year warranty and seem to have japanese capacitors, gold certification and fully modular cables, think this guy should be enough for the time being. Reviews that I found claimed that these series are quite decent. =))

 

[PC Tailor]

I bought a bit more expensive FSP Hydro G 850 w it has 5 year warranty and seem to have japanese capacitors, gold certification and fully modular cables, think this guy should be enough for the time being. Reviews that I found claimed that these series are quite decent. =))

I'd say that's a great choice - the G series is good. Around Tier 2 and has much better test results: you can see the 650W of the same line here on Toms: https://www.tomshardware.com/reviews/fsp-hydro-g-650-power-supply,4462-10.html - usually the japanese caps are a much more reliable shout in general and FSP are a solid reputable brand for PSUs

I'd say you've made a great choice there - yes it's not the best of the best - but it's a solid choice and I really don't think you'll need to upgrade that at all for quite a while and should easily last the 5 year warranty that it gives!

It really does pay to know that your components are being looked after and should be safe in the case of a problem! and I guess most importantly, thank you for taking the time to research into it to! I hope we've at least been helpful my friend.

 

[Satan-IR]

Yeah, it's the one. And here's some reviews of it: https://www.techpowerup.com/reviews/Cougar/CMX_850W/ . I'd be glad to buy a fancier PSU, but I'm budget tight as of now =((, I'll do that in a year or so when I'll start assembling something more powerful with better cpu and latest GPUs. If I'm making a huge mistake buying this one please tell me =)).

Yes that Cougar unit was not a good quality one for my comfort to run two powerful GPUs. In the same review you posted, as noted, it failed one of the ripple measurement tests. That's not a good sign. They test baed on ATX specifications and frankly when a PSU fails even a single one of them I think it's syb par and should be avoided. As PC Tailor pointed out that unit has not so good ripple suppression and that could mean an early grave for all components including graphics cards.

It also has Teapo electrolytic capacitors and CapXon polymer ones. Teapo is made in Taiwan, not bad quality but not as good as Japan-made ones. Polymer caps are generally more resistant to heat and ageing and do not die under pressure as often as electrolytic ones but CapXon is generally not reputed as maker of good quality. Some call them CrapXons!

Not a huge mistake but I'd go out on a limb and call it not-the-best-of-moves to choose that one for your system, or indeed any system.

Your other choice, however, is a very good one. PC Tailor also posted the link to the review of the 650W unit which I think is basically the same design as your choice; they just change components with different capacity of same make/quality to achieve higher outputs in the 750W and 850W iterations. This here is I think is an acceptable review of the exact 850W model. Good choice all around considering your budget and I too would think it would last the 5 years without problems.

However, if as you said later on you want to move to a system with 3-4 cards you'd need to upgrade the PSU as well. Hope all goes well and enjoy rendering at twice the speed!

 

[MeshVoid]

Guys, I need your wisdom again. I have watched this video:

View: https://www.youtube.com/watch?v=lqzGslhRolk&
. It's about buying used Intel Xeon E5-2689 processor that can be purchased for a dirt-cheap price of aliexpress and has a performance comparable to Ryzen 7 Performance for just around $50. I was thinking about ordering Xeon E5-2690 with a Chinese motherboard, basically it will take me 130-150$ to have a processor in a motherboard that is 100% more powerful multicore-wise than my i7 3770 as of now. Also that motherboard has 3 PCI Express 3.0 slots and should be better overall than my old one. As for memory I can just pluck in my 4x8gb ddr3 1600 cards into this motherboard and it should work the same. The reasoning behind this is to get better performance in viewports as Blender 2.8 is going to be released in a month and it is aimed at multithreaded performance, it should theoretically give me a huge boost when I'm working in the viewport. Although, i7-3770 has better single-core performance. Do you think this a good solution overall?

P.S. Here's some user benchmarks of two processors:
https://cpu.userbenchmark.com/Compare/Intel-Xeon-E5-2690-v2-vs-Intel-Core-i7-3770/m13436vs1979

https://versus.com/en/intel-core-i7-3770-vs-intel-xeon-e5-2690

https://www.cpu-monkey.com/en/compare_cpu-intel_xeon_e5_2650_v2-80-vs-intel_core_i7_3770-322

 

[MeshVoid]

Ah, disregard that, it won't help. Viewport performance is heavily dependant on single-core performance, so I'll have problems earlier with this setup.

 

[PC Tailor]

No problem - sorry we didn't respond sooner!

If you ever have any more queries, feel free to start a new thread so that more people can join in with their expertise.
Just remember that if you are happy, to select a best answer in this thread so that others can also see the solution should they need it my friend 👍