they _do_ fail in this way, but only under heavy abuse. I have cooked a 
5k200 before myself, but it was after some very bad mistreatment. The 
machine had been on for about 7 months under my desk at work, sucking up 
dust and dirt and fuzz and never getting cleaned. Being aware of this, 
i was getting close to deciding it was time to open it up and clean it 
out. The machine decided the matter for me, when in the middle of working 
it crashed to the chevron, and then wedged completely. There was no further
contact with the machine. I opened it up and it was _full_ of dust, a 
huge massive giagantic dust bunny the shape of the interior of a 
DECstation was covering everything. Im amazed the machine didn't die 
sooner! the poor thing had baked itself to death in there. In any case, 
as long as you keep the machine clean, it will run practically forever.
On one of them which ive had running more or less 24/7 for years now 
(though the highest uptime i got on it was 672 days, before i powered it 
down to upgrade it from a '240 to a '260 cpu) , i have twice now opened 
up _while_ running, and vacuumed out the dust.. :-)
Aside from some VAXen, i've never met a more indestructible computer than 
a decstation. (and some VAXen are flakier than DECstations!) 
so, keep your decstation clean and you'll never worry! 
also, while they have _very_ strong power supplies, as does most DEC 
stuff (when the power flickers and most peecees reboot, the DEC gear just 
keeps running), a UPS never hurts, as their tolerance for crappy power 
conditions will go down with age, the slow drift out of spec of 
components, and the degradation of capacitors. 

happy hacking,
isildur

> Then I also hear that these babies are prone to overheat and die,
> and as it is summer here it may just be that this was one season
> too much for this old horse.