Is this what you are talking about?
Interference with the Motherboard Components and Other Peripherals
If the northbridge heatsink that is 25mm or taller in height (measured from the motherboard's surface) is away from the AGP slot in the direction of the CPU by 5.5mm or farther, this product can be installed.
If CNPS7000 (Zalman's noiseless CPU cooler) is also to be installed, the CPU retention guide needs to be 35mm or farther away from the AGP slot for this product to be installable.
They also have a diagram.
I have a ZM80C-HP arriving in the mail today, however I have an Abit TH7-II which has an average sized chipset heatsink and plenty of room.