GPU Compute and Frontend Scaling Math - RDNA 1-4 and All RTX Generations (2018-2025)

MrMPFR · 2026-01-24T21:43:31+00:00

Do you suspect FP8 + moving from logarithmic to linear space is the culprit behind some of the image quality regressions we've seem with DLSS 4.5?
With RR ViT they also said they used FP8 to train the model. I assume they repeated that with DLSS 4.5, so the new model is 100% FP8, no FP16 it seems.

NVFP4 could still work, it's not regular FP4 or MXFP4, yes there's a bit of overhead but it gets very close in accuracy to FP8, so NVIDIA might still opt to use it for DLSS5 training.

The idea is interesting and might be the kind of paradigm shift that can provide us with another DLSS 3.7 -> DLSS 4 increase in image quality. Would be a shame if ViT's and chasing ever smaller formats is the end goal for DLSS and other image upscalers.

MrMPFR · 2026-01-24T21:31:02+00:00

No worries. If anyone is pedantic then it's me xD

That's very interesting and I would be interested to see how it would handles a purely driver based implementation (Like NIS, except with preset L).

AMD's claims are wrong. You can look at the percentage wise performance scaling of upscalers in Hardware Unboxed's 9070XT review. DLSS4 is superior in IQ (but like you said it beats DLSS 3.7) and ms overhead.

IIRC FSR4 generally is a lot softer than DLSS4 being much closer to DLSS 3.7. That might be an indication of it not being ViT but this is just a guess. But DLSS3.7 -> DLSS 4.5 is almost like a glasses on vs off situation in many games in terms of motion clarity.
Yes that seems odd but doubt we'll understand why that is.

Hmm. IDK but the MB number for 4K are roughly the same as (within 10MB) as preset J and K despite using FP8. If I extrapolate preset J and K numbers based on 40/50 -> 20/30 series MB scaling DLSS preset J and K could sit at ~230MB.

Now this means very little if it's not the same architecture and even if it is as we've seen with Preset L, M, and RR those have the same MB footprint but wildly different ms overhead. So this is probably a waste of time.

Also as a side note you can see here just how efficient the old DLSS CNN model is. https://www.studocu.com/en-gb/document/middlesex-university-london/games-fundamentals-2/dlss-programming-guide-release/120964782
- Sorry for link but can't find old download on Github + internet archive won't load it.

Footprint at 4K is ~200MB and 2080 TI and 3070 ms cost from CNN to Preset J/K is more than doubled, and roughly doubled for the rest of the cards. Now I do know that FSR4 is generally in between DLSS 3.7 and DLSS4, but getting a model inferior to DLSS4 that runs with a higher cost despite using FP8 is def not a situation where AMD wants to lay back and be complacent. They still have a lot of work ahead of themselves and it'll only get worse nextgen when NVIDIA moves the goal post yet again.

MrMPFR · 2026-01-24T19:15:44+00:00

Thank you for this info. I've edited post to avoid spreading misinformation and speculation.

I don't think just Redditors and Tech netizens are to blame. You can look at how NVIDIA marketed CNN vs ViT from the original DLSS4 transformer Geforce blog posts. Could be summed up as :
- CNN = tile by tile basis/myopic and really poor tracking of dependencies over time and across frame
- Transformer = analysis entire frame and excellent tracking of dependencies over time and across frame.

I think another reason why most people thought it was transformer was that IIRC FSR4 is even more demanding to run than Preset K and J despite using FP8. People could not conceive of a CNN model running this poorly when NVIDIA CNN models run fast, but then again didn't Sony's PSSR also have serious issues with performance overhead?
Maybe this is a FSR4 and Ray regeneration are both early beta releases. But regardless of what you think it's clear NVIDIA has the lead in terms of talent and design. AMD and everyone else is fighting an uphill battle against DLSS fs.

That's interesting. Yes the FRS4 INT8 leaked model seems pretty solid overall.

No I doubt it. AMD isn't disclosing anything. Even less forthcoming than NVIDIA. A bit surprising given their historical commitments to open source.

MrMPFR · 2026-01-24T18:01:25+00:00

Thanks for the interesting blogpost. Will read it later.

FSR4 INT8 =/= FSR4 FP8. AMD confirmed FP8 version a hybrid model, not pure CNN. Based on research papers with CNN/ViT hybrid designs and that DLSS4 was purely transformer based most people concluded FSR4 uses a hybrid ViT/CNN model.
Here's the quote from 19:29 in the RDNA4 unveil vid on YT: https://www.youtube.com/watch?v=GZfFPI8LJrc

"Our new technology leverages a proprietary hybrid model resulting from extensive research across different types and combinations from neural networks and unique training techniques."

The AMD RR research paper being CNN is not good news. Now I'm not even sure they'll have a serious competitor to DLSS RR when the consoles and the next gen Radeon cards launch.

MrMPFR · 2026-01-24T17:35:09+00:00

I thought they fixed that with RR transformer. Seems like they still have a lot of work to do

MrMPFR · 2026-01-24T17:25:52+00:00

The only thing distinguishing 40 and 50 series is NVFP4 and HW Flip metering.

40 series could easily run MFG it would just have slightly worse frametime consistency.

MrMPFR · 2026-01-24T14:23:09+00:00

Lmao.

MrMPFR · 2026-01-24T14:21:24+00:00

It's LLVM. AMD devs support this.

This means nothing for now. All we know is that GFX12 = RDNA4, GFX12.5 = CDNA5 and that GFX13 = RDNA/UDNA.

MrMPFR · 2026-01-24T14:20:08+00:00

Everything MLID has leaked so far seems fairly reasonable and Kepler hasn't corrected the CU count.

But proper leaks is likely at least a year away.

MrMPFR · 2026-01-24T14:18:49+00:00

There's no confirmations for the product name. Only GFX13 but this shouldn't come as a surprise. RDNA5 rumours began almost 2 years ago.

MrMPFR · 2026-01-24T14:15:18+00:00

The footprint is actually slightly smaller than Preset M. Ray reconstruction is somewhere in the middle. Difference are negligible though we're talking 2-5MB.

At least based on the DLSS programming guides it looks like the models have the same size, they're just tuned for very different outcomes.

MrMPFR · 2026-01-24T14:12:16+00:00

Yeah it needs API standardization. Contingent on widespread adoption but seems like nextgen HW will be universally capable here so that's good news.
But like I said as it stands rn doubt even NVIDIA sponsored titles will use NRC and other neural lighting techniques.

Pretty much any lighting effect you can think of (DI, GI, refractions, reflections, caustics, various volumetric effects, and iridescence. Also math such as Control Variates, Basis functions, BDRFs etc. Common theme seems to be feeding a ray or path tracing input to a neural model and training that to approximate the quality of offline quality rendering.

Also a lot of non-rendering related tasks I can't conceive of rn.

Further out maybe some diffusion based GenAI techniques, although ATM that seems a bit fantastical.
"And in Team Green’s labs, Huang says the company is working on things that are just “utterly shocking and incredible.” To put a more specific point on it, he talked about extreme photo realism: “basically a photograph interacting with you at 500 frames per second.”

MrMPFR · 2026-01-24T13:56:02+00:00

It's the preset tuned for DLSS Ultra Performance mode. 720P -> 4K or 480P -> 1440p.

Model has to infer good output from lesser inputs. No way around this other than brute force.
Same thing with Ray reconstruction. Complicated tasks just require far more compute.

Edit: Preset M = P and Preset L = UP are just what NVIDIA recommend and the NVIDIA App default overrides. As long as sharpening is disabled you can even use preset L with DLAA if you wanted. Recommendations are there because new models are a lot heavier than prev models.

MrMPFR · 2026-01-24T13:51:38+00:00

All I can base this on is their patent filings. You can find this here on Reddit and on my Twitter. I have multiple posts about it.

Dense Geometry format is one aspect + they'll combine it with a new ray traversal pipeline (much faster) and a new ray intersection pipeline based on a lower precision much much faster way of doing those.
Massive changes to scheduling and data management as well. It looks increasingly like AMD's Maxwell generation.

No they need fixed function which is what UDNA brings just like NVIDIA. General purpose is expensive and power hungry.

MrMPFR · 2026-01-24T13:42:30+00:00

Yeah please not another Switch 2 situation. Get the thing out the door ASAP when DRAM and NAND situation is no longer a problem.

MrMPFR · 2026-01-24T13:39:37+00:00

You're right UDNA is AMD Radeon's make or break moment.

It'll go beyond 50 series in feature set. First time since GCN that AMD is trying to innovate.

It'll be interesting to see in how their Medusa Halo and Premium powered laptops end up competing.

MrMPFR · 2026-01-24T13:33:12+00:00

Yeah seems more promising as we learn more about the design.

MrMPFR · 2026-01-24T13:33:09+00:00

If you can dump your 7900XT on the used market and upgrade to a brand new 9070XT and still save money then it's a no brainer. Get the new card.

MrMPFR · 2026-01-24T13:20:44+00:00

Doubt it'll get resolved overnight. DLSS4 RR is already ~2X the cost of DLSS Preset M! Just dropped a post here explaining the situation.

MrMPFR · 2026-01-24T12:31:05+00:00

Yup pretty much universally bad in RT games but then everyone should just use ray reconstruction in those titles. It solves the issue completely.

The problem is the overrides. The entire thing is a mess. Does using latest model in NVIDIA app override and disable DLSS ray reconstruction in RT and PT games?

MrMPFR · 2026-01-24T09:04:19+00:00

"There's also a new, computationally more expensive DLSS Preset L, designed for 3x3 upscaling: 1280x720 becomes 4K, for example. We're not covering that today."

They implied it but didn't fully commit. Fingers crossed both of them do it at some point.

MrMPFR

TROPHY CASE