Unless you're hardcore I'd highly suggest not getting an actual server, especially a 1U server like that. Servers are loud, use a lot of power, and especially in 1U form not that expandable. CPU and RAM upgrades are cheap, but say you want more drives, or to install some weird expansion card it might not have the space.

If photoprism is actually "AI" you'll want a GPU to do the processing, and 1U servers limit you to oddly sized 1U GPUs. But considering they say it will run on a raspberry pi I'd assume any desktop with a core i7 would do the job. If you can find a desktop with 4 ram slots of DDR5 that would get you plenty of expandability. The DDR5 spec is rated for up to 512gb per stick, so assuming the memory controller (and bios) supports it you'd be PLENTY future proof. But even DDR4 with 32gb sticks should be plenty, and those machines are CHEAP.

Your options will depend on many things...

• How much storage is needed?
• Is RAID important to you?
• Is power usage a concern?
• Noise level?

I don't know how demanding photoprism is, but you could probably do fine with a refurbished i5/i7 Dell Optiplex or similar, with one or more SSDs added to it. If money is really tight and storage needs are high, you could go with mechanical drives instead.

The problem with enterprise servers is that are generally very loud and use a lot of power...not unlike adding a second refrigerator to your environment. In my opinion, they're not worth it unless you have a specific use case (training for a career, etc.).

I'm assuming power efficiency and low noise are not a requirement?

As someone who has owned enterprise servers for self-hosting, I agree with the previous comment that you should avoid owning one if you can. They might be cheap, but your longterm ownership costs are going to be higher. That's because as the server breaks down, you'll be competing with other people for a dwindling supply of compatible parts. Unlike consumer PCs, server hardware is incredibly vendor locked. Hell, my last Proliant would keep the fans ramped at 100% because I installed a HDD that the BIOS didn't like. This was after I spent weeks tracking down a disk that would at least be recognized, and the only drives I could find were already heavily used.

My latest server is built with consumer parts fit into a 2U rack case, and I sleep so much easier knowing I can replace any of the parts myself with brand new alternatives.

Plus as others have said, a 1U can be really loud. I don't care about the sound of my gaming computer, but that poweredge was so obnoxious that despite being in the basement, I had to smother it with blankets just so the fans didn't annoy me when I was watching TV upstairs. I still have a 1U Dell Poweredge, but I specifically sought out the generation that still let you hack the fan speeds in IPMI. From all my research, no such hack exists for the Proliant line.

Remember, if your photoprism lasts more than 4 hours, consult a medical professional