i wonder,
once you install watercooling in a pc, does it have to stay there,
or doesn't it harm anything to take it out and put it in your new pc?

and how long does watercooling last before it dies on you,
is it like years, or only for pretty short term use?

Lasts as long as an aircooling setup, with proper maintainance.

Provided that the new PC has the right socket type to attach the blocks too, there's no reason you can't move it around. It's more work than just swapping HS's, but nothing beyond the norm.

ok, but if you spent lots of money on aircooling,
after lets say 6 months you might have gathered lots of dust in your case....won't that mess up your fans.... at least thats what i noticed in my system... my fans need cleaning,
so seems like installing WC might last a little longer then....

Unless you're running a passive water cooling system with just pump, but no fan(s), most water cooling setups still rely on at least one fan to move air through the radiator. A single 120mm fan is easier to maintain than multiple smaller fans, of course, and generally moves more air at lower noise levels and produces lower frequency signature noise (as I said, generally speaking).

The important thing to realize is that most liquid cooling systems need periodical maintenance; the period depends on the system, as well as the type of maintenance. I have seen users go 24 months without doing anything, and I've seen users that, every six months, have to drain the system out, flush it with a powerful mix of Pinesol/Lysol, and then refill the system. Most people have to at least drain the system every 12 months and then fill up with fresh coolant.

There are many variables that come into the equation, so it's not so simple as just saying, right from the get-go, that, "you only need to this and this every this many months," without actually building and running the system for yourself.

-Ed

interesting, thanx