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Comment by BoredPositron

3 days ago

Stop recommending 3090s they are all but obsolete now. Not having native bf16 is a showstopper.

Hard disagree. The difference in performance is not something you'll notice if you actually use these cards. In AI benchmarks, the RTX 3090 beats the RTX 4080 SUPER, despite the latter having native BF16 support. 736GiB/s (4080) memory bandwidth vs 936 GiB/s (3090) plays a major role. Additionally, the 3090 is not only the last NVIDIA consumer card to support SLI.

It's also unbeatable in price to performance as the next best 24GiB card would be the 4090 which, even used, is almost tripple the price these days while only offering about 25%-30% more performance in real-world AI workloads.

You can basically get an SLI-linked dual 3090 setup for less money than a single used 4090 and get about the same or even more performance and double the available VRAM.

  • If you run fp32 maybe but no sane person does that. The tensor performance of the 3090 is also abysmal. If you run bf16 or fp8 stay away from obsolete cards. Its barely usable for llms and borderline garbage tier on video and image gen.

    • Actual benchmarks show otherwise.

      > The tensor performance of the 3090 is also abysmal.

      I for one compared my 50-series card's performance to my 3090 and didn't see "abysmal performance" on the older card at all. In fact, in actual real-world use (quantised models only, no one runs big fp32 models locally), the difference in performance isn't very noticeable at all. But I'm sure you'll be able to provide actual numbers (TTFT, TPS) to prove me wrong. I don't use diffusion models, so there might be a substantial difference there (I doubt it, though), but for LLMs I can tell you for a fact that you're just wrong.

      3 replies →

Even with something like a 5090, I’d still run Q4_K_S/Q4_K_M because they’re far more resource-efficient for inference.

Also, the 3090 supports NVLink, which is actually more useful for inference speed than native BF16 support.

Maybe if you're training bf16 matters?