Homelab

It really depends. I've seen PCs that use nonstandard parts just so you must use original parts, and systems which made use of new things like 12 volt only PSU really early and had great designs for easy access in a compact machine.

I try avoid, on server sometimes its not possible.

I like Supermicro because have some ATX form factor MB with standard connectors

If the price is right, and parts are easy to find while not being a rip off, they're OK. You just have to ensure the machines don't have design problems that will lead to quick failures such as poor thermal management.

If they meet your need at your price level there’s no problem. For years, my homelab consisted solely of Dell boxes from eBay and the dell refurb site.

I built the latest one myself since it was the cheaper way to get all the features I wanted in a single box.

Second-hand hardware gets cheaper with time. Repair worker's labor doesn't. So there is price point below which complete replacement is cheaper than repair.

It really depends. For like a desktop, I'd avoid unless it was really cheap as I'd basically nullifies the value of all non standard parts and I'd include things like cpu if the motherboard is nonstandard. So value basically becomes only like drives and such.

For a server though, non standard is the norm and hete vendors even do stuff like vendorlocking instead which then IMO is a way bigger issue, especially since knowing beforehand if it does or not isn't something anyone actually tells you before testing.

I used to be all white box, and now I am all business class cast offs... If I lose a motherboard I can get one on ebay or a complete system for next to nothing if it is common like Dell. And now I just treat the boxes like cattle rather than pets. One dies and I move the hard drive to a new one.

Yes because they're cheap.

My thoughts on buying a system with proprietary components...

Pros

1. Buying typically is cheaper than building.
2. Saves the effort of matching hardware when DIYing.

Cons

1. Requires searching eBay (or other marketplace) for compatible proprietary hardware when a component fails.
2. Some proprietary systems (looking at you hp) can be picky with some replacement components like RAM.

If they are cheap then they are ok to buy in my opinion but when you are paying around as much for one as you would for a equivalent computer with standard parts then it is no longer worth it.

Really kinda depends on your use case.

For instance, if I'm building an ESXi cluster, then yea HPE all the way. It's quite trivial to find the option parts I need to complete the build and scour eBay for them. With those components tested and certified to work together I shouldn't have to worry too much about weird issues popping up.

Now, on the other hand, when building a NAS / SAN, I don't want to be locked into buying HPE branded disks so I opt for a Supermicro system. It doesn't care what brand of disk you use so I'm free to buy what makes sense for the type of datastore I'm creating,

Supermicro is also one of the few who build their server platforms on standard ATX / EATX form factors, so it's pretty easy to get the chassis you like and build the insides out however you like. Also makes upgrading the server internals super easy. Just buy a later gen components and transplant them. They're very good about making documentation and compatibility matrices available online

Cheap mini PCs have been my goto.

They are often powerful enough to get the job done, small, low power, quiet, and are easy to ship to sell if I want to upgrade. They may not be as reliable but I did the work on the software side to be able to easily replace or add new nodes.

as long as it's a proper brand like HP or Dell you should be fine finding parts on ebay etc...

If anything dies here i completely strip every single removable part, and keep it sorted in boxes. a lot of this stuff comes handy in places and can be upcycled on next builds.

Many of us use these in our labs. Dell servers, Cisco servers, etc. eBay, r/homelabsales and others are great resources for finding the "non-standard part".

Any proprietary hardware its just suitable for r/AssholeDesign

I wouldn't build a NAS in one of these unless it's like an older server or something. Mainly because these machines aren't meant for always on use and usually won't handle very well under random IO of something like ZFS. But if it's something like a one off Linx box or seed box like you said where you don't really care if it dies, that would be good. I know a lot of people in this sub also run a handful of these office machines for a Proxmox cluster or something like that where if one craps out, the others could take over

Just because they don't sell their own motherboards separately doesn't mean you can't stick a compatible motherboard in there.

All PC parts, including OEM, follow well established standards and are easily replaceable.