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I regret building this $3000 Pi AI cluster

(www.jeffgeerling.com)
468 points speckx | 6 comments | 19 Sep 25 14:28 UTC | HN request time: 0.211s | source | bottom
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Aurornis ◴[19 Sep 25 14:52 UTC] No.45302320[source]▶
I thought the conclusion should have been obvious: A cluster of Raspberry Pi units is an expensive nerd indulgence for fun, not an actual pathway to high performance compute. I don’t know if anyone building a Pi cluster actually goes into it thinking it’s going to be a cost effective endeavor, do they? Maybe this is just YouTube-style headline writing spilling over to the blog for the clicks.

If your goal is to play with or learn on a cluster of Linux machines, the cost effective way to do it is to buy a desktop consumer CPU, install a hypervisor, and create a lot of VMs. It’s not as satisfying as plugging cables into different Raspberry Pi units and connecting them all together if that’s your thing, but once you’re in the terminal the desktop CPU, RAM, and flexibility of the system will be appreciated.

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bunderbunder ◴[19 Sep 25 14:55 UTC] No.45302356[source]▶
The cost effective way to do it is in the cloud. Because there's a very good chance you'll learn everything you intended to learn and then get bored with it long before your cloud compute bill reaches the price of a desktop with even fairly modest specs for this purpose.
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Almondsetat ◴[19 Sep 25 15:06 UTC] No.45302469[source]▶
I can get a Xeon E5-2690V4 with 28 threads and 64GB of RAM for about $150. If you need cores and memory to make a lot of VMs you can do it extremely cheaply
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nine_k ◴[19 Sep 25 15:09 UTC] No.45302491[source]▶
It will probably consume $150 worth of electricity in less than a month, even sitting idle :-\
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blobbers ◴[19 Sep 25 15:15 UTC] No.45302573[source]▶
The internet says 100W idle, so maybe more like $40-50 electricity, depending on where you live could be cheaper could be more expensive.

Makes me wonder if I should unplug more stuff when on vacation.

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titanomachy ◴[19 Sep 25 15:44 UTC] No.45302909[source]▶
100W continuous at 12¢/kWh (US average) is only ~$9 / month. Is your electricity 5x more expensive than the US average?
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1. mercutio2 ◴[19 Sep 25 15:53 UTC] No.45303043[source]▶
Not OP, but my California TOU rates are between a 40 and 70 cents per kWh.

Still only $50/month, not $150, but I very much care about 100W loads doing no work.

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2. cjbgkagh ◴[19 Sep 25 16:26 UTC] No.45303494[source]▶
Those kWh prices are insane, that’ll make industry move out of there.
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3. selkin ◴[19 Sep 25 18:48 UTC] No.45305052[source]▶
Industrial pays different rates than homes.

That said, I am not sure those numbers are true. I am in California (PG&E with East Bay community generation), and my TOU rates are much lower than those.

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4. mrkstu ◴[20 Sep 25 01:58 UTC] No.45309384{3}[source]▶
If he’s only paying $50 most of it is connection fees and low usage distorting his per kWh price way up.
5. mercutio2 ◴[20 Sep 25 10:06 UTC] No.45311965{3}[source]▶
There are 3 different components of PG&E electricity bills, which makes the bill difficult to read. I am also in PG&E East Bay community generation, and when I look at all components, it’s:

Minimum Delivery Charge (what’s paid monthly, which is largely irrelevant, before annual true-up of NEM charges): $11.69/month

Actual charges, billed annually, per kWh:

  Peak NEM charge: $.62277
  Off-Peak NEM charges: $.31026
Plus 3-20% extra (depending on the month) in “non-bypassable charges” (I haven’t figured out where these numbers come from), then a 7.5% local utility tax.

Those rates do get a little lower in the winter (.30 to .48), and of course the very high rates benefit me when I generate more energy than I consume (which only happens when I’m on vacation). But the marginal all-in costs are just very high.

That’s NEM2 + TOU-EV2A, specifically.

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6. nullc ◴[20 Sep 25 17:46 UTC] No.45315507{4}[source]▶
Are you actually able to compute that? With PG&E + MCE because of the way they back off the PG&E generation charges, the actual per-time period rates are not disclosed.

I can solve for them with three equations for three unknowns... but since they change the rates quarterly by the time I know what my exact rates were they have changed.