A range of heatsinks produced by Zalman technologies.
Flower heatsinks are composed of 30-40 thin sheets of copper or aluminium which are stacked on top of each other, and bolted together at one end. The bolted end is machined to a mirror smoothness, while the other end is fanned, so that the heatsink resembles a book with its spine down, or a flower. The fan is held above the heatsink by a bracket that attaches to the blanking plate screws. The heatsinks are sold as boxed sets, containing a Flower, fan, bracket, a device to slow the fan, and a syringe of heat goo.

The big selling point for these heatsinks is their low noise output - Typically they are supplied with large, slow moving fans (often larger than a case fan). With the speed set to minimum, they are inaudible, drowned out by the hard drives or power supply. Even on full, they are still much quieter than equivalently performing conventional heatsinks.

The pure copper heatsinks are seriously heavy, weighing more that AMD and intel's maximum allowed weight. If the case is jolted, it can rock back and forth, destroying the processor, and if dropped, it is likely to snap off, damaging whatever it hits on the way down. Zalman warns customers to detatch pure copper heatsinks before moving the computer. There are also copper/aluminium Flowers that are just under AMD's weight limit, and pure aluminium ones that are under Intel's. For the truly hardcore, there's a gold plated one...

A common problem in installing a Flower is that the fan turns so slowly that the motherboard thinks it's broken, and won't switch on. By connecting a regular heatsink to the fan connector, this test can be disabled in the BIOS setup.