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Comment by kingsleyopara | Hacker News Reader

You might be able to get away with running a heavily quantizied 405b model using CPU inference at a blistering fast token every 5 seconds on a 7950x.

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OK, I am curious now: What kind of hardware would I need to run such a model for a couple of users with decent performance?

Where could I get a mapping of token / time vs hardware?

Unsure if anyone has specific hardware benchmarks for the 405b model yet, since it's so new, but elsewhere in this thread I outlined a build that'd probably be capable of running a quantized version of Llama 3.1 405b for roughly $10k.

The $10k figure is likely roughly the minimum amount of money/hardware that you'd need to run the model at acceptable speeds, as anything less requires you to compromise heavily on GPU cores (e.g. Tesla P40s also have 24GB of VRAM, for half the price or less, but are much slower than 3090s), or run on the CPU entirely, which I don't think will be viable for this model even with gobs of RAM and CPU cores, just due to its sheer size.

Energy costs are an important factor here too. While Quadro cards are much more expensive upfront (higher $/VRAM), they are cheaper over time (lower Watts/Token). Offsetting the energy expense of a 3090/4090/5090 build via solar complicates this calculation but generally speaking can be a "reasonable" way of justifying this much hardware running in a homelab.

I would be curious to see relative failure rates over time of consumer vs Quadro cards as well.

Agree 100% that energy costs are important. The example system in my other post would consume somewhere around 300W at idle, 24/7, which is 219 kWh per month, and that's assuming you aren't using the machine at all.

I don't have any actual figures to back this up, but my gut tells me that the fact that enterprise GPUs are an order of magnitude (at least) more expensive than, say a, 3090, means that the payback period of them has got to be pretty long. I also wonder whether setting the max power on a 3090 to a lower than default value (as I suggest in my other post) has a significant effect on the average W/token.

Agreed, but there are other costs associated with supporting 10-16x GPUs that may not necessarily happen with say 6 GPUs. Having to go from single socket (or Threadripper) to dual socket, PCIE bifurcation, PLX risers, etc.

Not necessarily saying that Quadros are cheaper, just that there's more to the calculation when trying to run 405B size models at home

The system I outlined in my other post [0] has ten GPUs and does not require dual socket CPUs as far as I'm aware. It could likely scale easily to 14 GPUs as well (assuming you have sufficient power), with an x8/x8 bifurcation adapter installed in each PCIe slot. This is pushing the limits of the PCIe subsystem I'm sure, but you could also likely scale up to 28 GPUs, again assuming sufficient power, by simply bifurcating at x4/x4/x4/x4 vs x8/x8.

I think it should work as-is with the components listed, but if you disagree please let me know!

[0] https://news.ycombinator.com/item?id=41047689

I don't think this is correct. 5 years power usage of 4090 is $2600 giving TCO of ~$4300. RTX 6000 Ada starts at $6k for the card itself.

https://gpuprices.us

To be fair, you need 2x 4090 to match the VRAM capacity of an RTX 6000 Ada. There is also the rest of the system you need to factor into the cost. When running 10-16x 4090s, you may also need to upgrade your electrical wiring to support that load, you may need to spend more on air conditioning, etc.

I'm not necessarily saying that it's obviously better in terms of total cost, just that there are more factors to consider in a system of this size.

If inference is the only thing that is important to someone building this system, then used 3090s in x8 or even x4 bifurcation is probably the way to go. Things become more complicated if you want to add the ability to train/do other ML stuff, as you will really want to try to hit PCIE 4.0 x16 on every single card.

With 2x 4090 you will have 2x speed of RTX 6000 A. So same energy per token.

Will need more space, true.

Yeah, after digging more into RTX 6000 Ada cards, I don't see any way they'd be more economical even over many years, no matter how you slice it.

You can run the 4-bit GPTQ/AWQ quantized Llama 405B somewhat reasonably on 4x H100 or A100. You will be somewhat limited in how many tokens you can have in flight between requests and you cannot create CUDA graphs for larger batch sizes. You can run 405B well on 8x H100 and A100, either with the mixed BFloat16/FP8 checkpoint that Meta provided or GPTQ/AWQ-quantized models. Note though that the A100 does not have native support for FP8, but FP8 quantized weights can be used through the GPTQ-Marlin FP8 kernel.

Here are some TGI 405B benchmarks that I did with the different quantized models:

https://x.com/danieldekok/status/1815814357298577718

The 405B model is very useful outside direct use in inference though. E.g. for generating synthetic data for training smaller model:

https://huggingface.co/blog/synthetic-data-save-costs

how much vram do you need for 4-bit llama 405?

405 billion * 4 bits = approximately 200 GB. Plus extra for the amount of context you want.

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