Locally Explains

The RTX 4090 Wins Until Your Model Hits Its 24GB Wall

Checked 15 October 2026.

Prices

Figure Value Source
RTX 4090, used going rate $3,500, the median asking price across 41 screened active listings (asking prices, not sale prices); cheapest screened pick $3,280 RigPrice, RTX 4090
RTX 4090, launch MSRP $1,599 RigPrice, RTX 4090
RTX 4090, new, cheapest in stock $4,299, Gigabyte Windforce at Amazon US; 90 day median $4,169 PC Tech Vault market watch
RTX 4090 desktop parts estimate (AMD build) $6,344.97 total, with an Asus TUF RTX 4090 OC at $3,649.22; that card, the case, the 4TB SSD and the power supply are listed as unavailable; prices updated 15 October 2026 Build My PC, RTX 4090 full guide
The same estimate with the current new card about $6,995 (6,345 − 3,649 + 4,299) arithmetic on the two rows above
MacBook Pro 14 inch, M5 Max 18 core CPU / 40 core GPU, 128GB, 2TB $6,699.00 Apple Store
MacBook Pro 16 inch, M5 Pro 18 core CPU / 20 core GPU, 48GB, 1TB $3,599.00 Apple Store
Step from the 48GB Pro to the 128GB Max $3,100 arithmetic
Price per gigabyte of unified memory M5 Pro 48GB about $75 (3,599 / 48); M5 Max 128GB about $52 (6,699 / 128) arithmetic

Specifications

Figure Value Source
M5 Pro memory bandwidth 307GB/s Apple MacBook Pro specs
M5 Max (40 core GPU) memory bandwidth 614GB/s Apple MacBook Pro specs
M5 Max unified memory up to 128GB (40 core GPU), on the 14 inch and the 16 inch Apple MacBook Pro specs
M5 Pro 48GB available on the 16 inch M5 Pro Apple MacBook Pro specs
RTX 4090 memory 24 GB GDDR6X, 1,008 GB/s NVIDIA Ada GPU architecture whitepaper; RigPrice
RTX 4090 board power 450 W RigPrice; NVIDIA whitepaper
1,008 against 307 3.3 times arithmetic
128GB against 24GB 5.3 times arithmetic

Benchmarks (published by others; different runtimes and settings)

Machine and model Result Source
M5 Max, Qwen3.8 27B 4 bit, MLX (mlx-vlm 0.6.14, MTP on) 853.75 prompt tok/s and 47.00 generated tok/s at depth 0 (2,048 token prompt); 36.05 generated tok/s at 8,192 depth NathanMaine/qwen-mlx-offline BENCHMARKS.md
M5 Max, Qwen 3.8 27B, MTPLX 2.10.0 64.3 tok/s on a 3k token chat answer; 30.4 tok/s decode and 535 tok/s prefill at 88k context; 18.4 tok/s at 147k MTPLX, run Qwen 3.8 on a Mac
M5 Max 128GB, Qwen 3.8 Flash Next, MTPLX 2.11 up to 84 tok/s on warm agent turns; 79.3 tok/s on a 9k token code prompt MTPLX
RTX 4090, Qwen3.8 27B UD-Q4_K_XL, llama.cpp CUDA, Q8 KV, native MTP about 2.4K prompt tok/s (2,436.59 on a 23,604 token prompt) and 65 to 75 generated tok/s at about 124K context window; prompt processing 1,741 tok/s at 97% context occupancy r/Qwen_AI community report
RTX 4090, Qwen3.8 27B at 160K context 47 to 57 tok/s, full GPU offload (a related r/Qwen_AI report) linked from the same r/Qwen_AI thread
M5 Max 128GB, Llama 3.3 70B Q4 (39.59 GiB), llama.cpp Metal, all layers on GPU 96.91 tok/s pp512, 7.23 tok/s tg128 guanxiong/setup-m5-pro bench results
RTX 4090 + Ryzen 7900 + 192 GB RAM, Qwen 3.8 Flash Next about 4,700 to 4,800 tok/s uncached 32K prefill; 120.10 tok/s at 32K; experts and the n-gram table stay in system RAM; “an active research checkpoint, not a claim of full-size quality parity” AnnoyingTechnology/nvidia-4090-flash-next-inference

Models

Figure Value Source
Qwen 3.8 Flash Next 125B total parameters, 6B activated per token (plus 51B of n-gram embedding tables held off the accelerator) arXiv 2608.30320
Llama 3.3 70B at 4 bit about 40 GB of weights (39.59 GiB Q4 file in the benchmark above) guanxiong/setup-m5-pro

Derived figures in the narration

Not checked