Heatercores are hazardous...
 

...to laminated wood!
http://home.pacbell.net/pqjack/warped.jpg

This is what a hot heatercore, after a long period of time, can do to your desk. You can see a large mark on the table in the shape of the HC, and it is very bumpy and warped.

It is a larger radiator, about 12x6. It was cooling my OC'ed XP passively, so it got pretty toasty after stressing the CPU for hours. But it was doing the job and the system only crashed when my room temp rose to 30C (85F) and I was stressing the system. I'd estimate that the water was getting up to 45C (115F!) during this time.

Just a warning to anyone thinking of leaving a hot heatercore on their desks or tables. If you're going to do it, at least put something under it. This doesn't apply if you are actively cooling with fans of course, unless you are using really wimpy ones.

http://home.pacbell.net/pqjack/warped.jpg click the link for the pic if it doesn't show up. I got a purdy red X! :D

Hum...I don't know... gotta ask:

Is the surface a simple melamine finish? Because those are very prone to the type of damage that you've got pictured, simply by getting the surface wet.

In any case, it's always a good idea to put something down on a purdy finished surface, if you're going to put car parts on it... (I'm guessing you're not married?)

I'm not sure what type of finish it is, all I can say is it's pressed wood with some kind of black laminant. No, I'm not married. I got the desk pretty cheap at Office Depot because it already had a few scratches, so I'm not too worried about it. It's not the water that's doing the damage; there were no marks from my reservoir (jug), so I think it's the heat. Well, I'm working on an enclosure so I don't have to leave the HC, pump, and res on my desk anyway. I just can't believe my HC actually got hot enough to warp the finish!