I regret building this $3000 Pi AI cluster

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.

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.

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

Source? That seems like something I would want to take advantage if at the moment...

Note the E5-2690V4 is a 10 year old CPU, they are talking about used servers. You can find those on ebay or whatever as well as stores specializing in that. Depending on where you live, you might even find them free as they are often considered literal ewaste by the companies decommissioning them.

It also means it performs like a 10 year old server CPU, so those 28 threads are not exactly worth a lot. The geekbench results, for whatever value those are worth, are very mediocre in the context of anything remotely modern: https://browser.geekbench.com/processors/intel-xeon-e5-2690-...

Like a modern 12-thread 9600x runs absolute circles around it https://browser.geekbench.com/processors/amd-ryzen-5-9600x

This is the correct analysis - there's a reason you see this stuff cheap or free.

The homelab group on Reddit is full of people who don't understand any of this - they have full racks in their house that could be replaced with one high-end desktop.