How fast will GPT-OSS 120B feel on the NVIDIA RTX Spark N1X 128GB (laptop)?

GPT-OSS 120B on the NVIDIA RTX Spark N1X 128GB (laptop)

GPT-OSS 120B is a 116.83B-parameter mixture-of-experts model (5.1B active per token). At MXFP4 it needs about 64.1 GB of memory. The NVIDIA RTX Spark N1X 128GB (laptop) has 119 GB usable, so it fits entirely in memory. Expect about 67 tokens/sec (53–81), with the first token after 0.3 s for a short prompt. This estimate is based on community benchmarks of this exact setup.

Speed by quantization

Quantization	File size	Memory	Generation	First token	Source
MXFP4	63.4 GB	Fits	67 tok/s	0.3 s	Measured

GPT-OSS 120B on other hardware

H100 80GB (cloud) · 528 tok/s at MXFP4
NVIDIA RTX PRO 6000 96GB · 282 tok/s at MXFP4
Mac Studio M5 Ultra 512GB · 208 tok/s at MXFP4
H200 141GB (cloud) · 193 tok/s at MXFP4
Mac Studio M3 Ultra 512GB · 158 tok/s at MXFP4
MacBook Pro M5 Max 128GB · 118 tok/s at MXFP4
Mac Studio M5 Ultra 256GB · 111 tok/s at MXFP4
Mac Studio M4 Max 128GB · 105 tok/s at MXFP4
AMD Ryzen AI Max+ PRO 495 192GB (Gorgon Halo) · 55 tok/s at MXFP4
AMD Ryzen AI Max+ 395 128GB (Strix Halo) · 52 tok/s at MXFP4
NVIDIA DGX Spark 128GB · 43 tok/s at MXFP4
NVIDIA RTX 5090 32GB · 31 tok/s at MXFP4
AMD Radeon AI PRO R9700 32GB · 29 tok/s at MXFP4
Intel Arc Pro B70 32GB · 25 tok/s at MXFP4
CPU-only (Ryzen 9 9950X, 96GB DDR5) · 22 tok/s at MXFP4
NVIDIA RTX 3090 24GB · won't run
NVIDIA RTX 4090 24GB · won't run
NVIDIA RTX 5060 Ti 16GB · won't run
NVIDIA Tesla V100 32GB · won't run
AMD RX 7900 XTX 24GB · won't run
NVIDIA RTX 5070 Ti 16GB · won't run
NVIDIA RTX 3060 12GB · won't run
NVIDIA RTX 5080 16GB · won't run
Mac mini M5 Pro 64GB · won't run
AMD Instinct MI50 32GB · won't run
MacBook Pro M5 Pro 48GB · won't run
AMD RX 9070 XT 16GB · won't run
AMD RX 7900 XT 20GB · won't run
MacBook M4 Pro 24GB · won't run

Other models on the NVIDIA RTX Spark N1X 128GB (laptop)

Qwen 3.6/3.8 27B · 7.8 tok/s at Q4_K_M
Qwen 3.8 Flash-Next · 35 tok/s at UD-Q4_K_XL
GLM-5.3 Flash · 21 tok/s at UD-Q2_K_XL
Gemma 4 26B A4B · 52 tok/s at Q4_K_M
GPT-OSS 20B · 60 tok/s at MXFP4
Qwen 3.5/3.6 35B A3B · 91 tok/s at Q4_K_M
Gemma 4 31B · 7.1 tok/s at Q4_K_M
Qwen 3.5 9B · 23 tok/s at Q4_K_M
DeepSeek V4 Flash · 26 tok/s at UD-IQ3_S
DeepSeek V4.1 Flash · 12 tok/s at Q2_K
Llama 3.1 8B · 27 tok/s at Q4_K_M
Gemma 4 12B · 18 tok/s at Q4_K_M
GLM-5.3 · 6.6 tok/s at UD-IQ1_S
Nemotron 3.5 Lightning 30B A3B · 54 tok/s at Q4_K_M

All models on the NVIDIA RTX Spark N1X 128GB (laptop) · GPT-OSS 120B on all hardware

Estimates for a short prompt on a single device. Measured numbers come from community benchmarks (r/LocalLLaMA, localscore.ai and more); others are derived from similar setups or projected from specs. Open source on GitHub.