Ryzen 9 9950X3D + RTX 5090 + 128 GB DDR5: four big MoEs with experts offloaded to RAM (Qwen3.8 Flash-Next 78.8 tok/s)

Name: Ryzen 9 9950X3D + RTX 5090 + 128 GB DDR5: four big MoEs with experts offloaded to RAM (Qwen3.8 Flash-Next 78.8 tok/s)
Creator: RigBase
License: https://creativecommons.org/licenses/by/4.0/

GPU(s)	RTX 5090 Amazon · eBay (used) · Newegg
VRAM / unified memory (GB)	32
CPU	AMD Ryzen 9 9950X3D (16 cores) Amazon · eBay (used) · Newegg
Motherboard
RAM	128 GB DDR5-5600 (4x32 GB) Amazon · eBay (used) · Newegg
PSU
Other	Arch Linux, NVIDIA 615.78, CUDA 13.4; GPU also drives the desktop (3 GiB kept free); runtimes keep hot experts in VRAM and the rest in system RAM
Reported total cost
Power

Measured speed (generation tokens/sec)

📏 How measured: reported by the original source; RigBase re-checked the numbers at that source

Model	Quant	Engine	tok/s	Details
Qwen3.8 Flash-Next	Unsloth UD-Q5_K_XL, MTP drafting, experts offloaded to RAM	Strata (296b59d)	78.8	⚡ spec-decode (MTP)
Ornith 1.5 122B	EXL3 4 bpw, 180/256 experts per layer in RAM, no drafting	TabbyAPI + ExLlamaV3 1.6.2	46.4
GLM-5.3 Flash	EXL3 3.05 bpw, MTP drafting, experts offloaded to RAM	Project Maya 1.1.21	30.1	⚡ spec-decode (MTP)
DeepSeek V4.1 Flash	Maya-S (experts 2-3 bit), partly streamed from SSD	Project Maya 1.1.21 (maya-ds4)	24.9

Seppe Gadeyne (dev.to), updated measurements 22 Oct 2026; median of 8 runs (Dutch prose + coding prompt), greedy, 512 output tokens. All four are MoEs with CPU offload of experts to system RAM: Qwen3.8 Flash-Next, Ornith, GLM-5.3 Flash and DeepSeek V4.1 Flash. Prefill at ~125K prompt: 4,252 / 1,508 / 2,445 / 2,570 tok/s in the same order. Versions: Strata 296b59d, Project Maya 1.1.21, TabbyAPI d6e6227 + ExLlamaV3 1.6.2.

Current GPU street price (estimate, not the builder's cost)

1× RTX 5090: ≈€6,199 each (≈$6,948), new, approx. price as of 2026-10-16, lowest listing on billiger.de (Asus GeForce RTX 5090 (lowest variant))

Estimated GPU cost for this build today: ≈€6,199
New retail prices in Germany incl. VAT; used cards are often much cheaper. Prices change daily.

Source: https://dev.to/seppegadeyne/four-big-local-llms-on-one-rtx-5090-and-128-gb-of-ram-benchmarked-side-by-side-2h8j

Blank fields = not stated in the source. We never estimate build data; GPU street prices above are separately sourced and dated.

Rent before you buy: try this model on a cloud GPU for a few dollars first: Runpod (referral link; sign up with Google to get the new-user bonus)

Quick answers: Can RTX 5090 run DeepSeek V4.1 Flash? · Can RTX 5090 run GLM-5.3 Flash? · Can RTX 5090 run Ornith 1.5 122B? · Can RTX 5090 run Qwen3.8 Flash-Next?