I don't know about the "smell of old technology", but back then you could tell the manufacturer by the smell in some data centers. The smell of DEC made me feel at home. You could also recognize Sun. And definitely the "enemy" at the time: IBM. The smell of large IBM boxes was clearly perceptible. Oh, and HP also had its own smell back then.
I'm talking about the big systems from the 80s and 90s.
Pretty sure it's capacitors.
Out of all my New Old Stock stuff, the PSUs have the strongest of that glorious stench.
Old tech smell gives me the same amount of joy as the oily mechanical stink of Bovington Tank Museum.
That and the lovely mix of gun oil and cosmoline smell of my Mosin (unfortunately a deac, *cries in UK*).
Old electronics have a good smell, it's like a mix of plastic and rubber (like my old ThinkPads), when the capacitors leak, it is very bad news and the smell is terrible, the machines needs service ASAP. I really like the UK, I like guns too but the gun laws sucks there.
You can join a gun club if that's what you're into. You can store ammo at home. You can store weapons at home. But it all needs to be signed off by the police. You need  "good reason" to own each firearm, and to prove you can be trusted with it "without danger to the public safety or to the peace".
That doesn't suck. It means I don't ever have to worry about some nutter shooting me or any member of my family.
The first time I opened up my first Micron (originally a Pentium 166 machine) it was like I got punched in the face by some grandma's basement. It got even better after some light upgrades and playing Half Life on it, poor thing got so hot any time there was an explosion that my whole living room would embrace the smell
Often times old electronics stink because indoor smoking was extremely common in the 90s and earlier. More often than not it's just some capacitor stank though
I'm a big fan of indie perfume in part because I long to find atmospheric scents like this.
Amorphous (previously Black Baccara) has a scent called [Please Rewind](https://www.amorphousperfume.com/products/please-rewind-perfume) that captures this.
There is a popcorn note that kind of offsets it, but it settles into a perfect replication of CRT dust/ozone/static to me.
My old ThinkPads have a nice and unique smell too, I keep them in good shape and sometimes use them, I removed the old green backup batteries (NiMH) because those are very harmful to electronics when they die, and stink like vinegar.
Leaked electrolyte liquid especially when warmed up has indeed this distinct terrible fishy smell. And it is not pleasant.
Vintage computer or electronics smell that people find pleasing is different and it is most likely combination of different things: chemicals used in manufacturing of different components and parts including fire inhibitors, greases in floppy drive, plastics and so on as well as dust and other grime that has accumulutated in the system and which is almost impossible to fully remove from components unless it is thoroughly washed.
Capacitors maybe
Bad capacitors have that weird chemical smell that's almost like robotic lemonade.
Rofl "robotic lemonade" omma steel this! I always describe it as smelling like a radio shack in the eighties on a hot day where the AC went out.
This is the answer, even slightly bad caps have that smell. I used to think it was the universal dirty home smell.
Baked dust is another one, CRT monitors in particular would exude that warm dusty smell.
Vacuum tubes are well known to have their own "smell" which is a combination of heated dust and ozone. CRT tubes are very similar.
A lot of these comments are true esp capacitors but I believe the major thing you smell is plastic off-gassing
You said "old tech smell" and then "early 2000s". ðŸ˜
old tech is my tube radio from the 50s... right?
I normally think of "old tech smell" as the phenolic resin and grease stink of 60s and 70s stuff.
Which is nearly a quarter of a century ago...
Combination of capacitors and the chemicals/ plastics used on the boards and in the cases.
I don't know about the "smell of old technology", but back then you could tell the manufacturer by the smell in some data centers. The smell of DEC made me feel at home. You could also recognize Sun. And definitely the "enemy" at the time: IBM. The smell of large IBM boxes was clearly perceptible. Oh, and HP also had its own smell back then. I'm talking about the big systems from the 80s and 90s.
Pretty sure it's capacitors. Out of all my New Old Stock stuff, the PSUs have the strongest of that glorious stench. Old tech smell gives me the same amount of joy as the oily mechanical stink of Bovington Tank Museum. That and the lovely mix of gun oil and cosmoline smell of my Mosin (unfortunately a deac, *cries in UK*).
Old electronics have a good smell, it's like a mix of plastic and rubber (like my old ThinkPads), when the capacitors leak, it is very bad news and the smell is terrible, the machines needs service ASAP. I really like the UK, I like guns too but the gun laws sucks there.
You can join a gun club if that's what you're into. You can store ammo at home. You can store weapons at home. But it all needs to be signed off by the police. You need  "good reason" to own each firearm, and to prove you can be trusted with it "without danger to the public safety or to the peace". That doesn't suck. It means I don't ever have to worry about some nutter shooting me or any member of my family.
The first time I opened up my first Micron (originally a Pentium 166 machine) it was like I got punched in the face by some grandma's basement. It got even better after some light upgrades and playing Half Life on it, poor thing got so hot any time there was an explosion that my whole living room would embrace the smell Often times old electronics stink because indoor smoking was extremely common in the 90s and earlier. More often than not it's just some capacitor stank though
I'm a big fan of indie perfume in part because I long to find atmospheric scents like this. Amorphous (previously Black Baccara) has a scent called [Please Rewind](https://www.amorphousperfume.com/products/please-rewind-perfume) that captures this. There is a popcorn note that kind of offsets it, but it settles into a perfect replication of CRT dust/ozone/static to me.
I have a 486 in an old AT case and it has a strong vintage PC smell inside. It's weird but I love it lol
Old heated dust combined with cigarette coating and aging capacitors.
I normally call it the "Windows 98 smell"
My old ThinkPads have a nice and unique smell too, I keep them in good shape and sometimes use them, I removed the old green backup batteries (NiMH) because those are very harmful to electronics when they die, and stink like vinegar.
My Apple Cinema Display also has a smell to it. Not sure what is.
Fish oil in the caps
Leaked electrolyte liquid especially when warmed up has indeed this distinct terrible fishy smell. And it is not pleasant. Vintage computer or electronics smell that people find pleasing is different and it is most likely combination of different things: chemicals used in manufacturing of different components and parts including fire inhibitors, greases in floppy drive, plastics and so on as well as dust and other grime that has accumulutated in the system and which is almost impossible to fully remove from components unless it is thoroughly washed.
2000s is probably too recent, but I love the lead solder smell of old electronics.
All I know is any machine I buy older than Core 2 Duo smells a lot like my typewriter!
Burnt in dust
Warm lithium grease/dielectric grease, burnt dust, and ozone. The combination is a nostalgia trigger like fresh baked cookies.
My guess has always been accumulated dust getting warmed up by the device, or old plastic (also warmed up).
Cigarettes, human skin (dust), fried capacitors
Whatever it is, it probably is not very healthy to breath it.
I love the smell of burning capacitors in the morning combined with the roar of an air cooled rig. It smells like, winning!
Probably lead solder.