Adding an Old Quadro P2000 to an RTX 3090 Cuts Ollama Speed, Not Extends Context

A developer tested whether pairing a Quadro P2000 (5GB, Pascal, 2016) with an RTX 3090 (24GB) could expand the usable context window in Ollama and vLLM running the qwen3-coder:30B-A3B model. The experiment found no increase in context capacity, with both single-GPU and dual-GPU setups hitting the same fatal 'Chunk too big' error at 65,536 tokens. Adding the older card actually degraded decode speed dramatically, dropping from 75.7 to 19.5 tokens per second at a context length of 49,152. vLLM rejected the dual-GPU configuration outright within 40 seconds due to the P2000's compute capability (6.1) falling below the minimum required (7.5) for modern quantization kernels like AWQ's Marlin. The findings highlight that compute capability compatibility must be verified before VRAM capacity when combining mismatched GPU generations for inference workloads.