Here's some of the basics about Mac serial numbers and why it's going to make sense to change it when you go from a 2012 Mac mini to a 2013 Mac Pro SMBIOS or "Product Name" (to make it Big Sur eligible).
Apple devices manufactured after 2010 generally have 12-character alphanumeric serial numbers, with the first three digits representing the manufacturing location, the following two indicating the year and week of manufacture, the next three digits providing a unique identifier, and the last four digits representing the model number. Starting in 2011 the serial numbers for Macs went from 11 to 12 characters.
View attachment 484892
Here's the Late 2012 Mac mini Server 6,2 specs:
The Apple Mac mini "Core i7" 2.3 (Late 2012/Server) features a 22-nm
Quad Core Ivy Bridge 2.3 GHz Intel Core i7 (3615QM) processor with
four independent processor cores on a single chip.
So lets say your current Mac mini 6,2 serial is this:
C07 J 5 0CF DWYN
The first 3 characters (C07) tell you that it was made by Quanta Computer in China. The Late 2013 Mac Pros were only assembled in the USA so already this serial doesn't correlate with your new SMBIOS of Mac Pro 6,1. The serials for all the 2013 Mac Pros start with F5K which means they were assembled in Fremont, CA and not it China. The four letters for the model number (DWYN) tell you it's a MD389LL/A or Core i7 Mac mini server model.
J tells you it was made in the 2nd half of 2012 and the week it was made by the number 5 which would mean September of 2012. If you have randomly generated and are using a Mac mini serial for a Late 2012 manufacturing date (there weren't any Trash Can Mac Pros even built that year), that is another glaring difference in the serial you are using with your new Mac Pro 6,1 SMBIOS.
Sometimes when you are having iCloud and iMessage issues you may have to call up Apple to fix problems. You'll want all the SMBIOS and serial, MLB and ROM info to match up with the Mac you are emulating. If you give them a Mac mini serial number and they check it, that's a major red flag when you've just said "I'm having problems with my 2013 Mac Pro being able to access iMessage or the MAS". It makes sense, doesn't it ?
You can use
Clover Configurator to generate new Mac Pro 6,1 serials and SMUUID etc. First open your Clover config.plist with CC. Then click the small box in the lower right corner of the SMBIOS section panel. Choose Mac Pro 6,1 or whatever else you want to change it to. Save your modified config.plist.
View attachment 484901
For those that have migrated to OpenCore the GenSMBIOS script is a good one to use.
Py script that uses acidanthera's macserial to generate SMBIOS and optionally saves them to a plist. - corpnewt/GenSMBIOS
github.com