And, funny enough, this was the first thing my manager asked me today, if a had a report with all our machines purchase date...I guess is budget session everywhere...
Regarding using the BIOS age as a purchase date, there are some caveats...
If you don't do BIOS updates, I totally agree that they are a close enough age indicator, and we use it also.
However, if you do REGULAR BIOS updates, thinks can get off track easily.
A real case, based on my own inventory, I have 11 Dell Latitude 5440 laptops in use, and their purchase date varies between January 2014 and April 2015.
BUT, Dell latest BIOS for these machines is from December 2019.
So, if we used it as a guide for the machine age, all these 5-6 years laptops would appear as 10 months old.
And this is worst for brand name machines, since they are (generally) longer supported than OEM motherboards...
In OEM motherboards, you should think that lower end boards would be supported (as in new BIOS would be launched) in smaller time windows, let's say 1-2 years, and high end motherboards would get BIOS updates for 4-5 years...
But in the real world, that's not always the case .... for instance, my trusty old home machine, with a Asus P6T-SE board, from 2009, only had BIOS updates until middle 2010. And although it's not a super-hyper-gaming board, it was high-endish when I bought it. At least my wallet thought that way...
On the opposite scale, at work, during 2006/2007, we bought about 600 low end motherboards, an Asus P5VDC-MX. It was a somewhat troublesome board, and Asus kept releasing BIOS for it, first BIOS version is from late 2005, latest version is from February 2010.
On our case, we have a mix of not doing BIOS updates, especially on OEM machines where we cannot easily automate it / do it remotely, and doing some BIOS updates on brand nanes, for Urgent security issues.
So, we have two reports, one that lists the purchase date , used for Brand name machines (simliar to the one I've sent) and one for OEM machines, which is very similar to the one CyberCitizen sent, I've copied from the forum some time ago.