I used a Palm handheld to keep record of my stuff for many years, and would probably still be doing that if Palm hadn't died.

About 10 years ago I started to transition everything to Microsoft Word documents, like so:

Easy to paste pictures. Easy to search for items by serial numbers, MAC addresses, and the like. Use different levels of headings (e.g. expansion cards -> PCI cards -> PCI video cards) and then Outline view to see simple lists of items.

H3nrik V! wrote on Yesterday, 21:21:

In theory, isn't all retro stuff, we do, that? 🤣

I guess you have a point. Haha. As long as you enjoy the process its not a waste of time.

I have a doc file of most of my hardware but I keep neglecting to update it. I usually impulse buy stuff or get it free and it sits for weeks, even months before I'm in the mood to tinker with it. By the time I get to something I don't remember where/how I got it and certainly won't remember to add it to the list. I kinda stopped with it for now.
I have 2 categories I'm meticulous with though, the CPU collection and the monitors. I have a thing for pre-90's monitors for some reason, especially those compact fugly hercules clones from the late 80's with the random color tubes. Whenever they turn up untested it turns into a game of "What color am I getting now?"
It's usually white but when it's amber I feel "jackpot!" So much fun.
I'm actually collecting CPUs so keeping a tight list is a must to avoid buying something multiple times and wasting money.
It's a never ending hobby.

I tried various things over the years - access database, spreadsheet, text files. In the end I just wrote an app to do the job and everything goes into that - spare parts and whole computers complete with photos, etc. Spare expansion boards/motherboards/drives go into an antistatic bag with is sealed shut with a label that has a database reference on it and some basic information while PSUs just get a label slapped on them somewhere:

For whole computers, a label with a database reference usually goes on the back somewhere and its database entry lists all the bits that are in it along with last test date, last battery change & type, last checked for leaking capacitors, photos, history, etc. I generally aim for enough detail/photos that I don't need to find the physical machine to answer a question about it. Some also get a webpage with more details (example), though I'm somewhat behind on adding complete PCs to the database as its a fairly time consuming process.

Currently I inventory: Displays, expansion boards, motherboards, PSUs, drives, cases and whole computers. RAM and CPUs aren't tracked individually and only have an identity for as long as they're installed in a computer/motherboard - I don't have enough loose CPUs to bother tracking, and I probably have more spare RAM than RAM slots for it to go into so its just sorted into anti-static bags by type/speed/capacity.