My next attempt was
to attach my CPUFX watercooler, however I had to modify it
to fit this Radeon board since it was designed for a
GeForce4. I also had to remove the metal frame on the Radeon
processor because it is about 0,1mm higher than the core.
Thus the water block would not make proper contact with it.
The standard cooler on the Radeon boards up to 9700 uses a
thermal pad that makes up for this 0,1mm gap. The 9800 uses
a special cooler with a very good thermal compound that has
had its bottom milled out so that it does not rest as much
on this metal frame, and thus it makes much better contact
with the core.

So what I did first
was to remove the cooler which was very easy because it is
attached with standard pushpin clips. When the cooler was
removed I used a sharp razor that I cut in-between the metal
frame and processor on all corners like this:

Be very careful not
to cut too deep with the razor and accidentally cut away one
of the tiny resistors on top of the processor package. When
you have cut all corners the frame will simply pop off when
you bend the razor carefully, what you end up with is this:

Next I tried
attaching my watercooler; I will not show pictures of that
because it was a failure. I had already done the volt-mod at
this stage and thought it was the volt mod that was causing
problems but in fact it was the watercooler not making good
contact so I just reattached the standard cooler again. If
you choose to go for watercooling I would recommend you to
buy a watercooler designed for specifically the Radeon 9X00
card.
Moving along I can
tell you the memory modules on the Radeon I tested where
quite sensitive to heat, in the other hand, the core seemed
to cope with high temperatures quite well. I will need to
test my card with a watercooler designed for it before
making any final judgment though, while the core might cope
with heat pretty well it produces an enormous amount of it;
in fact the card itself will act as a pretty good heatsink.
I read somewhere that it was designed specifically for this.
But thus the core will also heat the memory and power
circuit, which is not a good thing. For optimum results I
recommend water cooling for the core, heatsinks for the
memory and a fan blowing air over the card.