M3 Ultra (Mac Studio) vs GeForce RTX 5090 for Local AI
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Which GPU is better for local AI workloads?
A Mac Studio with M3 Ultra starts at $3999 with 96GB of unified memory, configurable up to 512GB \u2014 enough for 400B-class models at tight quantization. The RTX 5090 at $1999 delivers 32GB of GDDR7 at 1792 GB/s with 21760 CUDA cores, roughly 2.2 times the memory bandwidth and far higher tensor throughput, at a 575W TDP.
Spec comparison: what actually differs
The table below is computed live from our hardware database. Positive deltas favor the M3 Ultra (Mac Studio).
| Specification | M3 Ultra (Mac Studio) | GeForce RTX 5090 | Difference |
|---|---|---|---|
| VRAM | — | 32 | — |
| Unified memory | 512 | — | — |
| Memory bandwidth | 819 | 1792 | -54% |
| Memory type | — | GDDR7 | — |
| Memory bus | — | 512 | — |
| TDP | 270 | 575 | -53% |
| CUDA cores | — | 21760 | — |
| Architecture | Apple Silicon (M3) | Blackwell | — |
| Launch MSRP | $3,999 | $1,999 | +100% |
| Street price | $3,999 | $1,999 | +100% |
What about price?
Which one should you buy for LLMs and image generation?
M3 Ultra (Mac Studio)
Buy the M3 Ultra Mac Studio if you need 70B-class and larger models locally, giant contexts, or silent whole-desk operation.
Full specs & benchmarks →GeForce RTX 5090
Buy the 5090 if your models fit in 32GB \u2014 it is dramatically faster for the money and installs in a standard workstation.
Full specs & benchmarks →Is it faster for LLM inference?
Model selection is the deciding factor: models whose weights exceed about 32GB require the M3 Ultra\u2019s unified memory, while anything that fits in 32GB generates tokens roughly twice as fast on the 5090.
How does it handle image generation?
The 5090 is far faster for Stable Diffusion and Flux. Apple\u2019s Metal backends run image models but with a smaller optimization ecosystem.
Which AI models fit on each card?
Computed from our model VRAM database at Q4 quantization: M3 Ultra (Mac Studio) has 512 GB, GeForce RTX 5090 has 32 GB.
Fit only on the M3 Ultra (Mac Studio) (512 GB)
Fit on both cards
Frequently asked questions
Can an M3 Ultra run bigger models than an RTX 5090?
Yes. Configured with 256GB or 512GB of unified memory it loads 200B\u2013400B-class quantized models; the 5090\u2019s 32GB caps it near tightly quantized 70B.
Which is faster, M3 Ultra or RTX 5090?
The 5090, decisively, on workloads that fit its 32GB: 1792 versus 819 GB/s bandwidth and far more raw compute. The M3 Ultra wins only when capacity, not speed, is the constraint.
Is the M3 Ultra good for image generation?
It works via Metal-accelerated ComfyUI and Diffusers, but the NVIDIA plus CUDA ecosystem is faster and better optimized for Stable Diffusion and Flux.