The GeForceFX 5800 Ultra produces a lot of heat. Hence, the appropriately extravagant cooler. Cool air is sucked in by a fan, through a channel outside the PC case, and another fan conducts the warm air out of the case. A heatpipe dissipates the heat from the chip directly to the cooling fins, which lie in the flow of air leading out of the case. This takes up quite a bit of space, causing the card's dimensions to increase, with the consequence that the first PCI slot of the motherboard is completely covered by it. Even the back of the card is equipped with a large passive heatsink to ensure proper cooling.
Despite this complex cooling solution, the card becomes quite hot during operation. While testing the card in an open environment (i.e., outside of a PC case), the heatsink on the back of the card reached over 68° Celsius/ 154.4 Farenheit. In a closed PC case, the temperature should increase even more.