Builds

Mac Studio M5 Ultra vs. dual RTX 3090 for local LLMs

One quiet box with 256 GB unified memory against a 48 GB two-GPU tower. The Mac fits far bigger models; the 3090s have more bandwidth per GB.

Total

$9,499

Usable memory

192.0 GB

Llama-3.3-70B-Instruct Q4

Fits

Est. tok/s

13–22

$ per tok/s

$542

Parts

We may earn a commission when you buy through these links, at no extra cost to you. Prices are dated snapshots (2026-10-23 for parts; GPUs at list price unless marked used). Used prices come from one dated listing each.

Will Llama-3.3-70B-Instruct run?

Tok/s = memory bandwidth ÷ model weight size × a 45–80% efficiency band, calibrated on llama.cpp scoreboards. Mixture-of-experts models show only an upper bound ("up to"). How we estimate speed.

Fit checks

• Mac Studio M5 Ultra 256GB is a complete system: no PSU, case or board to pick.

Compared with: Dual used RTX 3090 build (48 GB) for 32B to 70B models

Total

$7,216

Usable memory

48.0 GB

Llama-3.3-70B-Instruct Q4

Won’t fit

Est. tok/s

—

PSU needed

1350 W

We may earn a commission when you buy through these links, at no extra cost to you. Prices are dated snapshots (2026-10-23 for parts; GPUs at list price unless marked used). Used prices come from one dated listing each.

Full Dual used RTX 3090 build (48 GB) for 32B to 70B models page

All models on this build

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