Planning a local Gemma 4 build: Is a single RTX 3090 good enough?

Reddit r/LocalLLaMA / 4/10/2026

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A Reddit user is planning a local setup to run Gemma 4 large variants, focusing on the 31B Dense (31B Dense) and 26B MoE models.
They are considering a single used RTX 3090 (24GB VRAM) and want to verify whether it provides sufficient memory headroom for practical inference.
The user notes that the 31B Dense model reportedly needs about 16GB of VRAM at 4-bit quantization, but they are concerned about running out of VRAM as they increase the context window.
They ask for real-world experiences and benchmarks from people running Gemma 4 31B or 26B MoE on a single 3090, including tokens-per-second generation speed and how much of the advertised 256K context is usable without out-of-memory errors.

Hey everyone. I am planning a local build to run the new Gemma 4 large variants, specifically the 31B Dense and the 26B MoE models.

I am looking at getting a single used RTX 3090 because of the 24GB of VRAM and high memory bandwidth, but I want to make sure it will actually handle these models well before I spend the money.

I know the 31B Dense model needs about 16GB of VRAM when quantised to 4-bit. That leaves some room for the context cache, but I am worried about hitting the 24GB limit if I try to push the context window too far.

For those of you already running the Gemma 4 31B or 26B MoE on a single 3090, how is the performance? Are you getting decent tokens per second generation speeds? Also, how much of that 256K context window can you actually use in the real world without getting out of memory errors?

Any advice or benchmark experiences would be hugely appreciated!

submitted by /u/LopsidedMango1
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