I can't really comment on commercial GPU blocks as I haven't seen any in the flesh, choosing to make my own. The main problem with The Radeon 9xxx is the shim. To ensure full and good core contact it will either need to be removed, a simple operation, but cards have been trashed doing this, or to have some shim relief designed into the waterblock. I prefer not to modify the card so design my blocks to avoid the shim. You'd have to investigate which commercial blocks have shim relief, as just the fact it says it fit's the Radeon 9xxx series is not a guarantee it has shim relief. Unless a GF4 block is also designed to fit Radeon 9xxx it wont have shim relief, (or the correct hole spacing), and even if it is designed to fit the Radeons, like I Said, this doesn't ensure it will avoid the shim.
The current 9800 pro reference sink has a raised core centre on the heatsink base, so ATI saw this as an issue and implemented the most simple fix solution, that laughably negates the point of the shim altogether
The Radeon 9xxx series have two diagonal retention holes that are the same as Geforce 3, (I've only had 9700 & 9800 pro only so others in the range may differ), Geforce 4 has a much wider hole spacing.
