I now own two of these renewed HP EliteDesk mini-PCs, and I couldn't be more happy with them.  They have a lot of computing power but take up almost no space, compared with a traditional desktop tower.  With both of mine I  replaced the Windows operating system with Ubuntu so that all my software is free and I don't need a Microsoft account.  Over the years I have purchased five "renewed" computers and have not had problems with any of them.  The mini-PCs don't have a CD drive, but I rarely need one, and when I do, it is easy to plug in an inexpensive external one with a USB cable, plug and play, no problem.  Also the EliteDesk minis have 7 USB ports, but external USB extenders are inexpensive if you need more.  The EliteDesks have quad-3GHz cpu's, 16GB RAM and 256GB solid-state storage, so they are snappy fast and silent.