Anything that does the job is good enough. At its core a server is just a regular PC with a dedicated purpose and software. Sure, there are specialized hardware better suitable and purpose built, but it’s not a requirement.

I for one prefer 19" rackmount stuff with disk bays in the front, but that’s more of a convenience than anything.

UPS is nice, but it’ll work without it.

I’ve had to deal with the Brazilian computer market and how it’s ridiculously overpriced due to import fees, so in your situation I’d just get any hand-me-down computer. Servers generally don’t require much unless you’re doing something special or intensive.

Get your hands on whatever you can find for free or dirt cheap (laptop or desktop doesn’tmatter), install linux, and you have a basic setup that you can work with. If your use case requires more, then that’s something you can accommodate in the next iteration of your server.

What are you intending to run on this server?

• If it is just PiHole, you can basically get the weakest computer you can find.

• If you want lots of storage space, you will need to make sure you have a case and motherboard that will accommodate the drives.

• If you are running encryption on those drives as well, you will need a CPU more powerful than what comes in a Pi, but nothing crazy.

• If you are running lots and lots of VMs, you will want lots of RAM. A linux VM will use maybe a few GB each depending on what software each is running internally, a windows vm will use a bit more.

• If you are doing AI workloads, you will need a graphics card.

Keep an eye out for people trashing perfectly good desktop machines because Windows 10 is being retired.

If you want a server that “does it all” then you would need to get the most decked-out top of the line server available… Obviously that is unrealistic, so as others have mentioned, knowing WHAT you want to run is required to even begin to make a guess at what you will need.

Meanwhile here’s what I suggest – Grab any desktop machine you can find to get yourself started. Load up an OS, and start adding services. Maybe you want to run a personal web server, a file server, or something more extensive like Nextcloud? Get those things installed, and see how it runs. At some point you will start seeing performance issues, and this tells you when it’s time to upgrade to something with more capability. You may simply need more memory or a better CPU, in which case you can get the parts, or you may need to really step up to something with dual-CPU or internal RAID. You might also consider splitting services between multiple desktop machines, for instance having one dedicated NAS and another running Nextcloud. Your personal setup will dictate what works best for you, but the best way to learn these things is to just dive in with whatever hardware you can get ahold of (especially when it’s free), and use that as your baseline for any upgrades.

The joke is electricity and Linux.

The real answer is the free hardware.

My main reliable is from 2008? It cannot do modern virtualization due to not having the CPU instruction sets.

Take a look at some N100 devices (or N95/N150).

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Find out if there are any corporate off-lease machines being sold in your area. USFF machines are frequently used as mini desktops or point of sale computers then sold off for peanuts when warranties are done. Especially look at i3-8xxx generation, as they don’t support windows 11 fully.