I've used tower PCs for about 30 years now, and most recently had a super-efficient Akermann PC which I bought in 2013 and which has given sterling service ever since. We moved to a new house about three years ago, and my home office is now in our small third bedroom; in addition, the fan has become very noisy.
So, I looked around for a replacement and my son-in-law pointed me at mini PCs, and at the ITZOO website. I did a search and came across this Elitedesk 800 Computer. It's not new, of course, but it has an excellent spec and a very good price. I paid an extra £50 to replace the hard drive with a 512Gb solid-state drive, and I am really glad that I did. The PC arrived in a couple of days and it was dead easy to set-up, although I made a few screw-ups in doing so. But got it up and running and I am really pleased with it. It's tiny compared with my old tower - I have it on its side, and the footprint is 180 x 30mm - and really fast. It's also absolutely silent, which is lovely. I'd recommend this to anyone looking for an inexpensive but efficient PC.
I'd also recommend ITZOO as a supplier. I had questions before I bought, and I've had a few questions over the past month or so since the kit arrived. They've all been answered clearly and at lightning fast speed. Their support desk is UK based, and the lady with whom I've been dealing is absolutely brilliant. Highly recommended all round.