With proper maintenance, I plan to get these working for at least 2 years time [Reboot and dust-off every week + full cleaning and basic maintenance every other month + full check and fan greasing twice a year]
taking the fans off to grease them may void the warranty.
rigs require surprisingly little maintenance, depending of course on the environment. i have a rig in the living room (mining/gaming rig) with all filtered intake fans. i vacuum them once a week. last time i took the side panel off a few months ago i didnt need to to a thing, and its run 24/7 for ~2 years now.
the open frame rig in the basement gets taken outside every 6 months or so and blown out with an air compressor. make sure you use a qtip or something and hold the fans when blowing towards the fans so as to not overspin them. thats it. that rig is also about ~2 years old, although i replaced the motherboard about a year ago as the old mobo was too power hungry (core 2 quad Q6600).
fans? just get good cards with ball bearing fans. sleeve bearing fans dont tend to last as long.
as for reboots, just when i update them. otherwise they go for months at a time until the power blips or i work on them. although reboots certainly wont hurt anything.
