This list will be longer than any other list on here. 🙁

Some big ones:
-every box for every game I bought. If I had the foresight to know their sentimental and real value, I'd be golden.
-a bunch of DOS and early Windows era retro hardware went in the trash when we did an out of state move some years ago. I had no appreciation for anything retro at the time. 🙁 Things like AWE64 Gold, Adaptec PCI SCSI controllers, a bunch of 486 and Pentium I, II and III processors, many graphics cards from the 486-Pentium III era.
-I donated my Apple IIe (complete with monitor, dual disk drives, and Mockingboard) to my old elementary school. Sounds like a great thing, but I did this long after the Apple II was popular with schools anymore. They may have used it a year or two then did their own recycling of it. I should've kept it.
-my first ever DOS PC--Packard Bell Legend 386sx-20.

I went many years in blissful ignorance, not caring that I threw these things out. Late last year, I happened upon Phil's YouTube channel, which led me here, and the retro fever started to rekindle, along with the regret. 😒

yea same here Ive been really getting into retro ever since i seen Phil's vids awhile back. i had about 5 of those packard bell legend 486dx ones

HP Vectra, desktop Pentium Pro 200. Doh!
FIC VA-503+ SS7 motherboard. Doh!

I have much better retro hardware now then I ever did back then though 😎

Nothing much. I'm glad it's all gone.

The monitor for my Dell 333P and an IBM pentium machine 🙁

I try to avoid throwing anything out, because when I do I always regret it.

One of the few things I ever tossed was a black Dell Trinitron CRT that came with the family's Dimension 8100 (which was also tossed, although not really my fault as I had no part in that decision seeing as I was 8 years old.) It had a gorgeous picture, but I threw it out because it "hurt my eyes". Because I was so used to maxing out the resolution on LCDs, I would always run it at 1600x1200 at 60hz and you can probably tell how that went.

And now I'm still kicking myself because I could never find any decent quality CRT monitors since then. (I have a Compaq but that doesn't count, it's blurry and the picture darkens a lot when displaying white.) It's like they went extinct in my area after that.

I threw out a bunch of 486 boards years ago (one had the capability of using both 386 and 486 and had motherboard cache. I did keep all the cache chips though and maybe a couple BIOS chips).

Ugh... don't even get me started.

While I'm glad I don't have even more junk that I've dragged around for decades, I could (but no longer) have in my possession:

Tandy 1000HX
Commodore VIC20
Commodore 64 with box, tape drive and lots of accessories
Atari 130XE + IndusGT and tons of games
Intelivision and Colecovision working, with boxes and games
NES, SMS, Genesis, SNES and all the games kept in pristine condition in boxes
Lots of awesome PC hardware that was outdated and gotten rid of one way or another... rarely for much if any money.

... its not like I cry myself to sleep thinking about these things, afterall, they are just "things"... but it does irk me to know that I kept so many other stupid things, packed away in my Mom's attic for far longer, and now I have an interest in the old computers and games again.

- My first 486 machine (DX2 66MHz with 8MB of RAM; 1993-1994 era ASUS motherboard; Soundblaster 16 with proprietary CD drive which I kept)
- My Apple IIe w/ Apple III green monochrome monitor and a single Disk ][ drive
- Two IBM PC Jrs, including one monitor, a mouse missing its special pad, and wireless keyboard
- A Pentium 166 non-MMX rig with 64MB of ram and a Matrox M3D

I purged most of this around 2008-ish when I was a stupid teenager because I was starting to have a hoarding problem and my parents wanted me to clean the basement. Truth be told, I wasn't big on the PC Jrs, but I still should of resold them at least. The one thing I actually regret getting rid of most is the Apple IIe, since it was such a neat machine. It had a really nice mechanical keyboard and the way the green phosphors on the monitor faded simply looked awesome,

I miss my green Apple monitor. 🙁 Aztec looked amazing on it. Although, I ended up using a TV when I could to experience games in color.

box of my DOS games. i usually kept them, but time came from all-powerful MOM to throw them out. Ugh. the horror.

Its cost me about $800 to get my collection back.

wow that's rough

3dfx voodoo2, or I trash it by mistake or it got stolen, the point is that I dont find it anymore 🙁 ... I dont care about using it anyway, game that use it are so ugly.

I just bought that card second hand for 20 bucks in ~2004 to learn to code in windows C++ 4.5 some 3d, so in between direct3d, opengl and glide, of course, and once again, I just took the right decision....

I tossed all my old game boxes (DOS era, early windows) around the late 1990's. Kept the game media and manuals but missed the boxes (filled a whole black trashbag).

Oddly I started getting into retro around 2001, so bad timing.

Well, not me, but an old friend of mine...
He borrowed my Commodore 386SX-16 machine because he was working on his own OS kernel, and wanted to have a machine he could experiment with, without having to worry about messing up his own box (this was the pre-VM era apparently).
When I got into oldskool PC democoding again a few years ago, I asked him if I could get the machine back. He told me he threw it out because it didn't work anymore (probably the PSU).
I was pretty miffed about that, because I could probably have fixed it, or at least salvaged various parts, including a beautiful WDC Paradise 16-bit ISA card with 512KB of memory (expanded it myself from the stock 256K).

IBM PS/2 model 50, complete with mechanical keyboard and an IBM color monitor. Fuck.

I threw it out about 12 years ago, when model 50s were still a common sight in thrift stores and alleyways. Now they're rare and quite expensive, like the rest of the PS/2 line. Or any 286/386 PC, really. But What hurts the most is that mine was in mint condition. I must've been drunk.

Long ago, complete decked out ti-99/4a, apple iie.

More because of the timing but had a big clear out in my parents garage when I went back to Oz in 2012, got rid of
Working Wang 286 and a 2nd parts PC.
12? Compaq Desk Pro P200MMX, all working
Few other bits like Asus Slocket adaptor.

Within 12 months and back in the UK I got back into old PC's in a big way. None of the PC's had any sentimental value, but now know I could have sold them and I know dad would have sent them to the landfill or at best recycling center 🙁

Oh dear...

- a ~1997 rather large HP Pavilion tower, I think it was a Pentium 233MMX. Notable for having an 8GB Quantum Bigfoot TX 5.25" HDD which I still have.
- a Gateway 386 system which was supposedly not working. It wasn't until much, much later that I found out that the ET4000AX video card it came with and kept after I threw most of the rest of the system back wasn't broken, all it needed were some DIP switches to be set... Also kept the 747-sounding HDD from that system as well: https://www.youtube.com/watch?v=a16CSy6Emto
- a 486DX-33 that was a hand-me-down from my dad. First computer I ever remember using. I ultimately wound up buying this to replicate that system.
- probably my biggest regret, my original K6 233MHz tower. The kicker was that it had a Voodoo 4 4500 AGP, which, as many of you know, is pretty uncommon nowadays. Inexplicably enough, I still have the box for that V4 somewhere in my house.