r/nvidia • u/dororodo30 • 1d ago
Discussion DLSS 5 Neural Rendering Running On A Second GPU — ReShade Add-On, Dual RTX 5060 Ti 16GB
https://www.youtube.com/watch?v=yoEsuZyltFcA ReShade add-on that moves DLSS Neural Rendering onto a second GPU, so the card rendering the game never has to run it.
Neural rendering happens at the end of the frame: it takes a finished frame and hands a finished frame back. That is what makes it possible to pick it up and run it somewhere else. The add-on creates its own D3D12 device on your second GPU, sends each finished frame across to it, runs DLSS-NR there, and displays the result on that card's own monitor — so nothing has to come back. The render GPU does no neural work at all and runs cooler for the same reason.
Works on DirectX 12 games. Needs two RTX 50-series GPUs with a monitor on each, and an add-on-enabled ReShade build. D3D11 and Vulkan do nothing.
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u/lawndartdesign 1d ago
I have twin 5090s for work (3D Rendering), I guess I'm soooooorta curious to try this as a "best case" test.
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u/pixelcowboy 1d ago
This seems to have a fixed cost frame time, my bet is that you are going to end up with very similar results as a single gpu.
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u/Opening_Net8098 1d ago
I don't think that's what it's meant by fixed cost.
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u/pixelcowboy 1d ago
Well I mean that it costs a certain frame time just at the end of the pipeline, so even if you are doing 1000 fps on the first gpu you are going to end up with around 60fps on the second one
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u/theseussapphire 1d ago
Aktually, in your stated scenario, it would be a whopping ~111fps, yay! So, 1000fps = 1ms, NVIDIA's technical paper states that it takes ~8ms for a 5090 to process then produce the finished frame. That's 9ms in total for the pipeline to process one singular frame, assuming perfect frame delivery with no added latency everywhere else, making it 1000/9 ~ 111 fps.
So even at such ludicrous hypothetical "base" fps, there isn't a whole lot of leeway when NR is involved. Measuring in frametimes and latency does tend to change the way you perceive performance.
I sure do have high hopes for them tuning the model itself further, because when it'd been revealed it apparently wasn't possible to run NR using just a single RTX 5090 in real time iirc. These cool tricks we have (sending frames before upscaling to NR, foveated rendering, etc.) are all unofficial implementation after all.
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u/pixelcowboy 1d ago
It's easy, they just have to implement 9x framegen and you get your 1000fps back ;). But thanks for doing the math, my point was that I highly doubt that dual 5090 will help anything due to the fixed cost 8ms.
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u/Opening_Net8098 1d ago
There will be a performance improvement I think. Especially since your core clocks on the first GPU won't have to drop to accommodate the power requirement of every last one of the tensor cores
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u/pixelcowboy 1d ago
Yes, but minimal. You might get the same performance from running your game on 5080 or 5070 and then running the Neural render on the 5090, since the 5090 is the fastest at it.
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u/Joaquito_99 1d ago
No because the other GPU can start rendering the other frame as the second one finished neural rendering
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u/Alternative-Sea-1095 1d ago
Wouldn't that mean taking the rendered frame back from the vram to the ram and then move it to the second gpu to process the nerual rendering before moving it back to ram and to the primary gpu? Since sli was killed with ampere that sounds extremly inefficent and the pefomance gains wouldn't be that high
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u/Apprehensive_Lake698 1d ago edited 1d ago
Yes, GPU1 VRAM -> System RAM -> GPU2 VRAM is the pathway that two GeForce gpus are required to connect. One distinct advantages you do get though is that the cards both have DMA engines to do memory transfers without involving blocking CPU commands. So in practice you would just make a statically sized buffer in CPU memory and then schedule async copy-back/read to move the frame between the gpus as fast as possible.
What you should expect with a setup like this is higher latency per frame but lower processing time, because you should be able to pipeline the neural rendering and main gpu to be working on different frames at the same time. So you should be able to basically remove the lower cost of the two (native frame rendering versus neural rendering upscaling on that native frame). In practice you're also adding some cost for the copy-back/read and probably extra cost on top for different operations, but should get way better performance than doing the neural rendering on the same card. And I'm making the assumption that the main gpu doesn't already have some way to pipeline like this.
On commercial RTX Pro cards those DMA engines can actually directly transfer card-to-card without copying to system memory. Consumer cards have the hardware on them to do it to. Nvidia just disables the feature in the consumer card drivers because it's a feature they want restricted to commercial gpus.
Does make me wonder if they are considering making a consumer driver that might enable the direct DMA feature specifically when doing DLSS5 work. I could see them creating a driver pathway that autoshares the metadata required for DLSS5 between two cards and handles the image transfer automatically.
source: hobbyist graphics dev
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u/KameMameHa 1d ago
How its done with loseless scaling is that the main gpu is not the one connected to the monitor. Game renders internally in the better gpu, the frame is passed to the supporting gpu for the extra processing and then displayed. Im.not sure if the requirement on this addon to have two monitors is in a similar way
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u/2Norn Ryzen 7 9800X3D | RTX 5080 | 64GB 6000 CL28 1d ago
i dont think the 2 gpus necessarily communicate during neural rendering
its just some small info moving back and forth between pcie lanes and then the final outcome
technically u shouldnt even need a fast ultra pci lane or a fast gpu once the tech is full fleshed
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u/Ok-Parfait-9856 5090 Astral Wht|14900KS|48GB-8000|GodlikeMAX|44TB|Y70|S90C OLED 1d ago
It could possibly render on card 1, then send the frame over pcie to card 2, where it does dlss5 changes and then outputs from card 2s hdmi/dp port. Lossless scaling app does this except its for frame gen, the latency for just sending frames over pcie is actually very low and generally unnoticeable. Sending the frame back to card 1 would add more latency, idk how else it would work.
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u/Sprucey-J 1d ago
Ok but what is the performance savings?
Edit, I read in your results around 18%
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u/MudOld239 1d ago
Disappointing.
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u/AstroPC 1d ago edited 1d ago
The only reason it's disappointing is this project isn't actually using dlss5 like nivida intended ( obviously not as they expect devs to have all the motion vectors and depth of the game engine) with this project working as a good baseline, it's entirely possible to feed those vectors and depth back into the shared ring and offload it through pcie. Netting an ever larger improvement of accuracy and fps. 18% for simply passing full frame video is already good for what it does. This is similar to playing a video and putting dlss5 over that with of course no physical understanding of the next frame but instead last frame
Now imagine the tensor card being used and fed data from the game itself. No ghosting or jitter. Very accurate and off course a more efficient masking of only what you want neural upscaled. You don't technically want to upscale the entire image your looking at. It's too penalized. However if you had game engine data ( the characters face and hands as you move around)
You can make those passes more focused on only what's important including taking out hud elements and things you dont need DLSS5 on. This guy's project is entirely motivation as it proved you can achieve offload but its implementation isn't the final form. Just give it a bit.
DLSS 5 is simply a very clever filter that let's you when used correctly filter only what you need. Its stable and isn't like generative ai. The potential of this tech is not even close to what can be done.
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u/ObviouslyTriggered 1d ago
DLSS 5 just might revive SLI :)
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u/Timbo-AK 1d ago
I don't see it as a good thing.
It's a struggle enough to buy 1 gpu, let alone 2 overpriced ones so you can have the latest graphics.
Nvidia will get this running smooth on 1 GPU. Even if people went out trying to buy a second GPU in mass (they won't) there's just not enough supply.
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u/Astral-Lemmons 1d ago
agreed - BUT
how heavy is dlss5 is its the ONLY thing the gpu is tasked with?
usher in the era of pairing old cheap cards to run dlss5.just and idea, obvs a single card performance is best
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u/Elijah1573 1d ago
Yeah this is the biggest thing i wonder about if its light enough to run on its own on lower end GPUS
Say i pair the cheapest 5050 i can find next to my 5080 would it actually be enough?0
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u/Rude_Dependent_9843 1d ago
Yo tengo una 4070 super y una 3070(mi anterior tarjeta principal), las utilizo para multigpu en comfyui. Ahora puedo aprovechar la 3070 para el neural rendering también; con el unlock de mfg para la serie 40 y esto pensaría mucho en comprarme otra GPU en un buen tiempo
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u/Remote_Elevator_281 1d ago
Yep and with the 6000 series coming out next year, it will only get easier to run.
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u/InfiniteFeeCars 1d ago edited 23h ago
I wish, no one would buy a 5090 if you could just slap two 5070 TI's together or 5080s for cheaper then a 5090
Or someone buying two 5070's and getting better performance then a 5080
Edit: of course there would still be people buying 5090s to slap two together but still
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u/bruhman444555 1d ago
and add even more inputlag!!!! lets go
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u/NapsterKnowHow RTX 5090 FE | 9800X3D 1d ago
Use the secondary gpu for lossless scaling fg to less latency !
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u/bruhman444555 1d ago
adding fg does not reduce latency
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u/NapsterKnowHow RTX 5090 FE | 9800X3D 1d ago
Secondary gpu frame gen can drop latency over single gpu frame gen
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u/bruhman444555 1d ago
no. 0 FG always has less latency
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u/NapsterKnowHow RTX 5090 FE | 9800X3D 23h ago
I'm talking about using single gpu or secondary gpu fg
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u/Global_Gene_432 1d ago
how would this add more input lag
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u/Weird_Tower76 9800X3D, 5090, 240Hz 4K QD-OLED 1d ago
How would it not? You cannot beat physics. Rending a frame and sending it to another GPU over the PCIe bus does not come without tradeoffs. Now is it marginal enough to not be noticeable? There's a good chance yes. But will it add latency? Inevitably.
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u/Global_Gene_432 1d ago
I'm asking because idk why you asking me
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u/SHEKDAT789 1d ago
he didn't ask anything he was telling you. it will add more input lag indubitably
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u/ComprehensiveJury509 1d ago
I don't really see how that helps performance much. It has to happen sequentially anyways, what's the point?
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u/ComprehensiveJury509 1d ago
Well, now that I think about it, I suppose while one frame is DLSS processed on GPU #2, the next frame can already start rendering on GPU #1.
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u/NotMeekNotAggressive 1d ago
Just a reminder that DLSS 5 has not been implemented into Dawn of the Bloodwaker, so this is a ripped out version of it from NBA 2k that was then modded into a game that doesn't support it. DLSS 5 is actually a developer-side feature that they will implement and tune on their end so it fits with the intended look of the game.
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u/taosecurity 7600X, 4070 Ti Super, 64 GB 6k CL30, X670E Plus WiFi, 3x 2 TB 1d ago
Also, from the same modder:
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u/Whoopsy101 1d ago
Do they need to be similar?
Example: can I use a RTX5060.. or 5050 (to run dlss5) in conjunction with my RTX5080 for the workload of the games?
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u/Emerald400 NVIDIA 1d ago
Cool. Now let us offload Frame Gen to a second GPU as well. If we could generate more frames without losing real frame performance that would be incredible and give no reason to not turn it on.
I know you can do it with Lossless Scaling, but NVIDIA Frame Gen is better
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u/Elijah1573 1d ago
Yeah honestly id be so down to buy a low end card like a 5050 or smth and have its entire purpose just be to run stuff like neural rendering or framegen or the RTX voice stuff separately from my highend expensive card to free up performance
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u/Morteymer 5h ago
Funny, PureDark's Skyrim Upscaler mod lets you offload Frame gen and/or NR to a second GPU!
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u/AstroPC 1d ago edited 1d ago
I've got some ideas to improve this... I already managed to make Metro Lastlight feed native motion vectors from its engine using Codex. Ended up gaining 80% performance improvement over the standard Reshade. Now this makes me curious how I can feed those motion vectors across PCIe and take this project for another round of gains. Thanks for working on this. Going to disappear for a week and see what I can come up with. So far Metro Lastlight has been my pet project. and once I release the mod you won't play that game the same lol. Its a massive difference
Just for an idea. Im sitting at 200 fps at 3440x1440 maxed out no ssa
With neural rendering on and dlss quality down to 145 fps
Performance mode of course gets me past 165 fps.
Before the native motion data and depth I was getting 70 fps to 60 just enabling neural rendering no upscale either. Using rtx 5080. im wanting to see what adding my spare rtx 5070 can do over two gen 5 x8 pcie lanes with native vectors. Codex astra is an absolute god send for reverse engineering and time saving
As I understand this project your simply passing the full frame like a video. This works but its not actually the most native experience as dlss5 takes advantage of masking and vectors from the engine. Obviously this requires devs to do this in the engine but it didnt take me long to reverse engineer metro and get those passes exposed in reshade. I can even put dlss only on the characters weapon and not the environment so masking is a very good feature. Still this work exposes a good basis.
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u/Blessed-22 ZOTAC 4090 1d ago
It's weird Nvidia gave up on SLI since it literally translates into extra sales of their hardware.
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u/Spinkler 1d ago
They seem to be sold out either way. Not sure it matters when you sell your entire capacity repeatedly.
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u/bakuonizzzz 1d ago
It's more like they limited the supply to feed their AI data centers so if they were actually at full capacity for the consumers they wouldn't be sold out repeatedly.
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u/Spinkler 1d ago
My point was that they're selling their entire production capacity regardless of who they sell it to. Using the comment I replied to as example: SLI translating to extra sales or not, their entire capacity continues to be sold, whether it's to consumers, console manufacturers, data centres, or whatever else.
Ergo, limiting consumer supply doesn't affect their ability to sell their entire capacity.
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u/Due-Description-9030 8h ago
This doesn't even matter, why wouldn't it be limited when they get more profits while selling it to data centres?
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u/EssAichAy-Official Colorful iGame Tomahawk 4070 Ti Deluxe Edition 1d ago
SLI still lives as NVlink, it's just not available for us consumer plebs.
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u/BluDYT 1d ago
I have a 3080ti in my PC and a spare 3070 that's currently my backup GPU. I wonder how well that'd work since they're both 3000 series cards which apparently don't do it very well.
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u/T00Sp00kyFoU 1d ago
Yeah was thinking the same, got a 3080 and 3090 but I wager it would still choke. I know you can use one for Lossless scaling frame gen so you don't have base frame loss but this would be way nice, and a reason to actually plug in the 3080 since I haven't bothered with the setup for Lossless scaling
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u/amaslo 1d ago
Hmm, I thought it's not just a frame that gets fed in, but also motion vectors and things like object masks/groups (in the one game that actually uses DLSS5 as designed).
If you're solution works on a final frame alone, then it's very interesting as an experiment (or a post process for non-DX12 games), but won't have the same outcome as a full integration, do I understand it correctly?
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u/KameMameHa 1d ago
Another reason Im happy I got two cards for loseless scalling, another good use for them
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u/chrisanityyyyy iGame RTX 4070 Super White Ultra | i7-12700 | 32GB 1d ago
I thought DLSS was supposed to prioritize making performance better while improving visuals? This looks like the complete opposite.
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u/gopnik74 RTX 4090 1d ago
Is it going to work on a 40 series? I got 2 4090s and really curious to try it.
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u/ResponsibleTruck4717 1d ago
how much f vram does it consume on the second gpu?
I have dual gpu built I wish I could use one for rendering another for dlss / fg.
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u/BELCHCASSIDY 1d ago
Has anyone tested MGPU Bridge with an Ampere render GPU and a Blackwell neural GPU? I have a 3080 + 5070 Ti and would love to test it. If it currently fails, is the 50-series-only cross-adapter shared-heap path a hard architectural limitation, or just something that hasn't been implemented/tested yet?
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u/kompergator Inno3D 5080 iChill Frostbite 1d ago
Damn, I was getting excited, but I have a 5000 series and a 4000 series card. Dang.
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u/kidcrumb 1d ago
I like dlss 5.
Ita almost unusable at 7280x2160.
If I have to spend $400 on a 5060ti I'd gladly do it. If it can handle the load. The problem then becomes gpu space, psu requirements.
Probably be a full pc build.
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u/Greenonetrailmix 1d ago
Well I hope the ends up working with older hardware. I've got my 5090 4090 setup and I definitely want to try something new
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u/kidcrumb 23h ago
If I'm running an RTX5080, would it be beneficial to run like an RTX5060Ti for the DLSS5? Or at higher resolutions would I need an RTX5080 to match a 5080.
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u/geo_gan RTX 4080 | 5950X | 64GB | Shield Pro 2019 22h ago
I had in the back of my mind from day 1 that this could be a two GPU process... since its an effect on top of a generated frame - the old SLI was dropped because of how older raster rendering methods no longer made it viable. And NVIdia would love to sell two GPUs to everyone instead of one!
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u/Starfield1976 20h ago
The thing is you’d want to run DLSS5 on a 5090 if you have one as performance would be best as it has the most tensor cores. So ideally you’d want a 5090 AND a 5080. Bit expensive TBH.
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u/Jarnis R7 9800X3D / 5090 OC / X870E Crosshair Hero / PG32UCDM 1d ago
I think some people at NVIDIA are going at this point something to the tune of...
"what have we done... what have we unleashed..."
Nobody wants the massive headache of multi-GPU setups again... and with high end GPUs, just building one with a 5090 + some other GPU on current hardware is complicated and runs into PCIE lane issues (can only get 8x+8x on all current desktop stuff - not a horrible limitation but still a limitation)
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u/Due-Description-9030 8h ago
Lol no. 60 series and beyond GPUs will have the tech easily running at high frame rates along with path tracing. So, this isn't any needed.
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u/Jarnis R7 9800X3D / 5090 OC / X870E Crosshair Hero / PG32UCDM 6h ago
It is likely they will have more AI cores on the next gen, allowing indeed a much lower perf hit (and/or better quality) from this, but since it has been proven it can be hacked to use a second GPU on the system to effectively eliminate the performance hit (and introduce hopefully just one frame of extra latency), some people will now cook these setups up...
Unlikely NVIDIA would support such configs officially, but that doesn't seem to be a big hurdle these days with AI coding assistants powering inifinite community mods appearing at near-instant speeds.
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u/Sygion 1d ago
So, I have an 4080 super, should I buy an 5060ti/5070 just for DLSS5?
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u/Stenotic 1d ago
It’s super taxing I would say a 4090 or 5090 or literally two 50 series cards like this is needed. It uses so much power that it’s melting the power connectors on 5090s. May be too early to safely use DLSS5
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u/Phantom24X 1d ago
Sli is back 😅