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Building a personal, private AI computer on a budget

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Re: Building a personal, private AI computer on a budget

#41

Isn't the fact the P40 has horrible fp16 performance a deal breaker for local setups?

You probably won't be running fp16 anything locally. We typically run Q5 or Q6 quants to maximize the size of the model and context length we can run with the VRAM we have available. The quality loss is negligable at Q6.

But the inference doesn't necessarily run at the quant precision.

Re: Building a personal, private AI computer on a budget

#42

One reason to bother with private AI: cloud AI ToS for consumers may have legal clauses about usage of prompt and context data, e.g. data that is not already on the Internet. Enterprise customers can exclude their data from future training. https://stratechery.com/2025/deep-research-and-knowledge-val... > Unless, of course, the information that matters is not on the Internet. This is why I am not sharing the Deep Res…

ToS can change. Companies can (and do) act illegally. Data breaches happen. Insider threats happen.

Why trust the good will of a company, over a box that you built yourself, and have complete control over?

Re: Building a personal, private AI computer on a budget

#43

One reason to bother with private AI: cloud AI ToS for consumers may have legal clauses about usage of prompt and context data, e.g. data that is not already on the Internet. Enterprise customers can exclude their data from future training. https://stratechery.com/2025/deep-research-and-knowledge-val... > Unless, of course, the information that matters is not on the Internet. This is why I am not sharing the Deep Res…

Cost for one

Re: Building a personal, private AI computer on a budget

#44
post #26
post #17

The author mentions it but I want to expand on it: Apple is a seriously good option here, specifically the M4 Mac Mini. What makes Apple attractive is (as the author mentions) that RAM is shared between main and video RAM whereas NVidia is quite intentionally segmenting the market and charging huge premiums for high VRAM cards. Here are some options: 1. Base $599 Mac Mini: 16GB of RAM. Stocked in store. 2. $999 Mac M…

The issue with Macs is that below Max/Ultra processors, the memory bandwidth is pretty slow. So you need to spend a lot on a high level processor and lots of memory, and the current gen processor, M4, doesn't even have an Ultra, while the Max is only available in a laptop form factor (so thermal constraints). An M4 Pro still has only 273GB/s, while even the 2 generations old RTX 3090 has 935GB/s. https://github.com/g…

That's a good point. I checked the M2 Mac Studio and it's 400GB/s for the M2 Max and 800GB/s for the M2 Ultra so the M4 Ultra when we get it later this year should really be a beast.

Oh and the top end Macbook Pro 16 (the only current Mac with an M4 Max) has 410GB/s memory bandwidth.

Obviously the Mac Studio is at a much higher price point.

Still, you need to spend $1500+ to get an NVidia GPU with >12GB of RAM. Multiple of those starts adding up quick. Put multiple in the same box and you're talking more expensive case, PSU, mainboard, etc and cooling too.

Apple has a really interesting opportunity here with their unified memory architecture and power efficiency.

Re: Building a personal, private AI computer on a budget

#45
I doubt it is that efficient. Even though it has 48GB of VRAM, it's more than twice slower than a single 3090 GPU.

In my budget AI setup I use 7840 Ryzen based miniPC with USB4 port and connect 3090 to it via the eGPU adapter (ADT-link UT3G). It costed me about $1000 total and I can easily achieve 35 t/s with qwen2.5-coder-32b using ollama.

Re: Building a personal, private AI computer on a budget

#46
post #17

The author mentions it but I want to expand on it: Apple is a seriously good option here, specifically the M4 Mac Mini. What makes Apple attractive is (as the author mentions) that RAM is shared between main and video RAM whereas NVidia is quite intentionally segmenting the market and charging huge premiums for high VRAM cards. Here are some options: 1. Base $599 Mac Mini: 16GB of RAM. Stocked in store. 2. $999 Mac M…

Worth pointing out that you "only" get If that is enough for your use case, it may make sense to wait 2 months and get a Ryzen AI Max+ 395 APU, which will have the same memory bandwith, but allows for up to 128GB RAM. For probably ~half the Mac's price.

Usual AMD driver disclaimer applies, but then again inference is most often way easier to get running than training.

Re: Building a personal, private AI computer on a budget

#47

The problem for me with making such an investment is that next month a better model will be released. It will either require more or less RAM than the current best model- making it either not runnable or expensive to run on an overbuilt machine. Using cloud infrastructure should help with this issue. It may cost much more per run but money can be saved if usage is intermittent. How are HN users handling this?

There is also an overlooked “tail risk” with cloud services that can end up costing you more than a a few entire on-premise rigs if you don’t correctly configure services or forget to shut down a high end vm instance. Yeah you can implement additional scripts and services as a fail-safe, but this adds another layer of complexity that isn’t always trivial (especially for a hobbyist).

I’m not saying that dumping $10k into rapidly depreciating local hardware is the more economical choice, just that people often discount the likelihood and cost of making mistakes in the cloud during their evaluations and the time investment required to ensure you have the correct safeguards in-place.

Re: Building a personal, private AI computer on a budget

#48
post #32
post #17

The author mentions it but I want to expand on it: Apple is a seriously good option here, specifically the M4 Mac Mini. What makes Apple attractive is (as the author mentions) that RAM is shared between main and video RAM whereas NVidia is quite intentionally segmenting the market and charging huge premiums for high VRAM cards. Here are some options: 1. Base $599 Mac Mini: 16GB of RAM. Stocked in store. 2. $999 Mac M…

For sure and the Mac Mini M4 Pro with 64GB of RAM feels like the sweet spot right now. That said, the base storage option is only 512GB, and if this machine is also a daily driver, you’re going to want to bump that up a bit. Still, it’s an amazing machine for under $3K.

It would be better/cheaper to buy an external Thunderbolt 5 enclosure for the NVME drive you need.

Re: Building a personal, private AI computer on a budget

#49

The problem for me with making such an investment is that next month a better model will be released. It will either require more or less RAM than the current best model- making it either not runnable or expensive to run on an overbuilt machine. Using cloud infrastructure should help with this issue. It may cost much more per run but money can be saved if usage is intermittent. How are HN users handling this?

> expensive to run on an overbuilt machine

There's a healthy secondary market for GPUs.

Re: Building a personal, private AI computer on a budget

#50

The problem for me with making such an investment is that next month a better model will be released. It will either require more or less RAM than the current best model- making it either not runnable or expensive to run on an overbuilt machine. Using cloud infrastructure should help with this issue. It may cost much more per run but money can be saved if usage is intermittent. How are HN users handling this?

I think the solution is already in the article and comments here: go cheap. Even next year the author will still have, at the very least, their P40 setup running late 2024 models.

I'm about to plunge in as others have to get my own homelab running the current crop of models. I think there's no time like the present.

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