Thanks for the input, guys.
Remonster: I seem to have a revision 2, since the door does not open all the way, and I got the wire brackets
. Would seem like the way to go, since I have five drives - four in the bottom cage, and my boot drive in the top cage. However, the X1950XTX is quite large, not sure a fan will fit behind the drive cage. Perhaps it may fit in front of it - there seems to be a bracket there.
Chozart: Nice cable management there - now I must seriously reconsider my own - it's not nearly as neat. That must help airflow a lot too - I have an annoying flat IDE cable to the DVD, always been a cause of grief... Did you remove the top exhaust fan, or is it just not visible on the picture? It seems a bit overkill to have the two exhaust fans up there so close, when the Zalman fan sits just below the top one, and in front of the rear one.
How's the temp on your drives with the lower fan removed?
Anyway, it is definitely lack of airflow, since if open the side of the case, CPU temp drops 10 degrees C...