[No compensation of any kind was received for this review.]I'll state this first:  I like this machine a lot, and I'd buy another immediately if I had need for one.  It is a superb box for running Linux.  That said, buying one of these is not for the faint of heart:  you need to expect, err, adventures.The adventures have two main sources:  a) HP sold many different computers named “EliteDesk 800”, and b) these are refurbs, i.e., devices with some previous life.  Each factor has the potential to sour your experience.Start with (a):  The  specific machine being sold here is correctly named “HP EliteDesk 800 G2 Mini”.  Not only was there a G1 series of these computers, there were at least three very different G2 EliteDesk 800 computers:  a Tower version, a Small Form Factor version, and the Mini.  There were also 35W and 65W versions of the Mini, as well as some regional variations.  Neglect to nail down the precise variant, and problems ensue.Example:  My Mini arrived with 16GB of RAM but I wanted to upgrade to 32GB.  Amazon's ConfirmedFit tool pointed me to the “right” RAM panels.  Hey, they won't fit!  That's because Amazon's tool ignored the “Mini” part of the specification.  ConfirmedFit swears that I need panels for RAM sockets about 5 in. wide.  [When the Mini's case is barely 7 in. wide??]  My Mini's RAM sockets are about 3 in. wide.  Fortunately, Amazon is great about returns.A vendor that specializes in RAM recommended the exact same panels as Amazon ConfirmedFit, and also told me I could install four of them.  Maybe the 800 G2 Tower has four RAM sockets 5 in. wide, but the Mini has exactly two sockets, each 3 in. wide.Consider (b).  First, your Mini may arrive with a dead CMOS battery; mine did.  It's an ordinary CR2032 lithium cell, and trivial to replace.  In fact, when you open your Mini's case for the first time, replace that battery:  it's likely several years old and will soon fail.Next, HP's Hardware Reference Manual says: “Internal WLAN antennae are standard on all HP G2 Desktop Mini models.”  My Mini simply does not have those antennae, nor did it have a WLAN card.  There is a socket for the card, just where the manuals dictate, but it was empty on arrival.  [So if you're having wireless connection problems, check to see if your specific Mini even HAS a WLAN card.]I conclude that a previous owner of my Mini didn't want users connecting via wireless, and so instructed the IT department to remove the critical parts.  It hasn't been a huge problem for me because I prefer the ethernet port [which works great], but down the road I might just need wireless.It's easy (and inexpensive) to install a wireless card in that empty slot, and the HP manuals will show you exactly how.  But you have to be willing to take that adventure, if need be.  [And if you go that route:  you'll need a teeny little screw to hold down the card (which will arrive without screw), and you'll likely also need to install antennae (the external style is easiest)].And then there can be issues of uncertain origin.  Example:  my Mini arrived with a Samsung 256GB M.2 PCIe “system” SSD.  I wanted more space there, so I bought a similar 500GB SSD, planning to retire the original.  No such luck.  The HP manuals show you exactly how to replace that card, but on my Mini it's impossible.  Why? Because the teeny little screw that holds it down won't budge.  I couldn't remove it; neither could a friend who's a full-time computer repair guy, nor could any of his coworkers.  My friend's conjecture:  at some time in the past, that screw was dipped in crazy glue.  Why?  I've no idea, and I also don't know whether to assign the blame to (a), to (b), or to the reseller.Still, the 800 G2 Mini has a great design and it packs a punch.  I gave it a new 1TB SSD and use the original as secondary storage.  Kubuntu 20.04 installed easily and runs just fine.  Aside from the adventures described above, my only problems have been in getting some Windows software to run via wine, and that's no fault of this machine.  Even those problems are merely irritating, not disastrous.  One of those Windows programs is at this moment running a big simulation on my Mini, and it's running far faster than it did on the Win7 box that the Mini replaced.This a good buy provided you're a little brave, even though the included keyboard and mouse are definitely landfill fodder.  But a final word of warning:  the On/Off button is at the right edge of the front bezel, and it is WAY too easy to turn off the Mini by accident.UPDATE:  Well, it's been in service for about 15 months now, with HEAVY everyday usage.  No problems of any kind.  I'd give it 4.5 stars if I could; it loses 0.5 stars only because of the issues already described.  Definitely one of my better buys.