I went through a similar ordeal back in November 2011 when my Athlon XP 2000+/Abit KT7A build went up in smoke. The smell filled my room and was very strong for over a year; I finally toned it down with generous use of air fresheners. It's still around faintly though, particularly in the wall area where the PC was close to.

The burned-out parts were a different story; nothing could get rid of the smell, even when sitting outside on the backyard for close to 6 months. Eventually my relatives and neighbors got fed up with it and was told to get rid of them. I had no other choice left.

I also have an old Maxtor 4GB hard drive that has a strong burn smell; like your PSU it fills the room after a short time, yet nothing appears out of place - no burn marks, no bad or missing electronic components. I keep it inside a box with foam padding to keep the odor in check. It still works, but will probably end up scrapping it.

In the end, you may have to just get rid of the PSU. You could try leaving it inside a closet with baking soda and activated charcoal for a number of weeks/months, and if you're daring take the PSU apart and clean the case and circuit board with isopropyl rubbing alcohol; don't be surprised if the smell doesn't disappear completely, though.

Put a few of these in the PSU.
Make sure they do not make contact with anything hot or you will get a new fire 😉

@jayceebee64 - yep that's all too similar. i used all sort of solvents and cleaners on the case - nothing helped.

looks like i'll chuck the psu.

@skyscraper - interesting idea, i had silica gel down as justbeing hygroscopic, does it absorb other things than water? either way, i move my stuff around so the "keep of hot components" means it's probably not something i should do.

thanks all

Yes the silica gel do absorb bad smell aswell, but Im not really sure how effective it is.

Tuck a fridge-box of baking soda into your CPU case!

You could try a packet of activated carbon, like they sell in pet stores for aquariums. It is good at absorbing odors and chemicals. If it is as bad as you say, though, it may not be enough.

Supposedly letting the components sit in baking soda or kitty litter can eliminate the smell, but then you've got the whole "my components are covered in baking soda or kitty litter" problem. If you're fine opening the PSU up, you may try cleaning the case with something strong smelling - I wouldn't use isopropyl here, I'm thinking of something like PineSol instead. I'd also consider replacing the fan itself - I've had fans in the past pick up "bad odors" and it seems like it just permeates them.

Of course, if the PSU isn't anything special or rare, I'd probably just recycle and replace and save the hassle.

The case itself I can't imagine being impossible to get smelling better - absolute worst case scenario sand it, prime it, and re-spray it.