The Mac Mini series of desktop Apple devices started with the G4 Mac Mini in 2005. The first Intel processor (Polycarbonate shell) versions appeared in 2006, with a 32-bit “Yonah” Core Solo processor. They are usually very good install targets for OpenBSD.

Intel Macs are generally Okayish to install OpenBSD on.

• Before 2014 most Mac Minis had upgradable RAM.
  • Mid-2010 and Mid-2011 models could be upgraded up to 16Gb of RAM, albeit “officially” they only supported up to 8Gb.
  • Mid-2010 models needed an EFI ugprade first to do this which came with MacOS 10.7.5. (source)
• First gen (Early/Late 2006; Macmini 1,1) models could be upgraded to essentially become a Macmini2,1 by swapping out the CPU / RAM and updating the EFI, but only The Hard Way.™ Tutorial here. The needed EFI update files were still available on mediafire on 2025-08-14.

According to EveryMac,

Compared to the “Late 2012” Mac mini models, the “Late 2014” line very much represents a “one step forward, one step back” kind of progress.
The “Late 2014” models have more advanced processors and much faster graphics, as well as Thunderbolt 2 capability, improved HDMI support, faster Wi-Fi, and a lower introductory price. However, they also are much slower than the “Late 2012” line in multicore tasks overall, no longer have Firewire support, no longer have RAM that can be upgraded, and no longer support two 2.5“ storage drives, either.

… and also,

Compared to the “Late 2012” Mac mini models, the “Late 2014” Mac mini models are between 1% and 9% faster in single core tasks but between 5% and 43% slower in multicore tasks:

Our conclusion: possibly get a 2012 Mac Mini over a 2014 one.

• A1993 Macmini 8,1
  • Late 2018 - MRTR2 (3.6Ghz i3 and 3.2Ghz i7 models)
  • Late 2018 - MRTT2 (3.0Ghz i5 and 3.2Ghz i7 models)

• A1347 Macmini7,1
  • Late 2014 - MGEM2
  • Late 2014 - MGEN2
  • Late 2014 - MGEQ2

• A1347 Macmini 6,1
  • Late 2012 - MD387
• A1347 Macmini 6,2
  • Late 2012 - MD388 (2.3Ghz i5 and 2.6Ghz i7 models)
  • Late 2012 - MD389 (2.3Ghz and 2.6Ghz i7 models; Server)

• A1347 Macmini 5,1
  • Mid 2011 - MC815
• A1347 Macmini 5,2
  • Mid 2011 - MC816 (2.5Ghz i5 and 2.7Ghz i7 models)
• A1347 Macmini 5,3
  • Mid 2011 - MC936 Server

• A1347 Macmini 4,1
  • Mid 2010 - MC270
  • Mid 2010 - MC438 (Server)

* A1283 Macmini 3,1 (Penryn)

• Early 2009 - MB463
• Early 2009 - MB464
• Late 2009 - MC238
• Late 2009 - MC239
• Late 2009 - MC408 (Server)

• A1776 Macmini 2,1
  • Mid 2007 - MB138
  • Mid 2007 - MB139

• A1176 Macmini 1,1 (Yonah)
  • Early 2006 - MA205 (32-bit)
  • Early 2006 - MA206
  • Late 2006 - MA607
  • Late 2006 - MA608

• TBC

• Mac Mini on Wikipedia