I put the Accelero S1 on my x1900xt. It is by far the best option because it has no fan and is completely silent. HOWEVER! If you are going to do any gaming, you must bump up the fan speed of your PCIe/HDD fan using smcFanControl The great thing is that if I am going to boot in to Windoze to play a game, all I need to do is choose a setting I named 'Gaming' in the smcFanControl menu and reboot in to windows. It retains the settings until you power off the computer. So as long as you reboot in to windows... the fan speed sticks. Even after having bumped the PCIe/HDD fan speed up, it is still quieter than the stock ATI cooler ever was. If I decide that I don't like having to use software to control the fans, I will purchase a quiet fan from silenx The S1 came with a vented PCI slot cover. Because the x1900xt already had one, I placed the extra one in the slot above to give plenty of ventilation for the hot air to escape If you google "Accelero S1" you will find some good reviews. One thing worth mentioning is that the vram heatsinks do not stick very well. I was able to get them to stick long enough to install the main heatsink. I am hoping that the heat will bond them... I will check them later to see if they are stock on there after being heated and cooled a few times.