SamplerDPMPP_3M_SDE_SUN

DPM++ 3M SDE is the overachiever: where the 2M variant remembers one previous denoised state, 3M remembers two, giving it the most accurate higher-order corrections in the stochastic family - and the highest cost. SamplerDPMPP_3M_SDE_SUN wrapped that solver with the pack's signature tweak: replacing the per-step Gaussian noise with scaled uniform noise on [-sigma_down, +sigma_down], deterministically seeded from the sampling seed, to dodge the high-CFG oversaturation that SUNoise research blames on Gaussian's extreme tail values.

Here's the part that matters if you found this page looking for the node: it's been removed. All six of the pack's per-sampler nodes - this one included - were deleted in the July 2024 "Complete rework, breaking changes." Current installs of bvhari/ComfyUI_SUNoise (v2.0.0) ship only the selector nodes SamplersSUNoise and SamplersSUNoiseAdvanced, and dpmpp_3m_sde survives as one entry in their dropdowns.

What it was

The node's interface was minimal: eta (default 1.0) and s_noise (default 1.0). No solver_type, no r - the 3M solver's structure doesn't expose those knobs the way 2M SDE and plain SDE do. That's a small hint at its character: 3M SDE is a "set it and forget it" expensive sampler, not a tweaker's toy. Output was a SAMPLER for SamplerCustomAdvanced, like everything else in this pack.

What to do with it in a workflow

A workflow saved between April and July 2024 may reference this class_type. When ComfyUI flags it as missing, the fix is boring and correct: swap in SamplersSUNoise, set sampler_name = dpmpp_3m_sde, pick standard or multires. You keep the third-order solver and the uniform-noise idea, and you gain v2.0.0's interleaving - SUNoise alternating with standard Gaussian every other step instead of pure uniform throughout, which fixed the slightly-too-smooth look of the earlier versions.

Only pin the old commit (git checkout efc6e38 in the custom_nodes folder) if you need byte-identical reproduction of an old pipeline. For everyone else, that's a downgrade.

Install, briefly

cd ComfyUI/custom_nodes
git clone https://github.com/bvhari/ComfyUI_SUNoise

Restart, or install via ComfyUI Manager → search "SUNoise". No dependencies beyond what ComfyUI ships, no model files, GPL-3.0. The pack has essentially no community chatter, so this page is the entire "known issues" section.

Bottom line

3M SDE is a quality-first sampler that most people don't need to reach for - 2M SDE gets you 90% of the way at a fraction of the cost. If your old workflow used the SUN version and you liked it, the modern equivalent is one dropdown choice away, on better noise. And as the README has always said: give it 30 steps or more.