Device: Apple M3 Ultra (256GB)
Category: mac
Memory: 256 GB (unified), usable for models: 192 GB
Memory bandwidth: 819 GB/s
MSRP (USD): 3999
TDP: 270 W
Best runtime: MLX direct / Ollama (MLX backend)
Notes: Max config Mac Studio M3 Ultra (2025). 75% rule at ≥64GB = 192GB usable. The 512GB config was discontinued in March 2026; 256GB remains available. Supports the largest open-weight models (405B+) at reasonable quants.