IBM AS400 eServer and I-SERIES whirring error free for the last ten years.
Seriously, my two machines have been running fairly continously except when they have been loaded into moving trucks to migrate around the country chasing their nomadic nerd owner (aka Me) . Bloody good machines. But now that these old machines can only run upto IBM i Version 5.4 I'm considering sunsetting them in favour of using a new IBM Power Server.
Sadly IBM's corporate pricing structure is purely focussed on B2B sales. Poor consumers like me are stuck with IBM refusing to sell small machines to students and/or little independent programmers like me, this basically means that I have to choose between spending $5000+ on a computer or on a new motorcycle :)
Maybe I just gotta stick with a ten year old operating system and admire my black boxes, supporting a beer fridge and homeserver.