Hello. I have a 2007 Intel 24" iMac (Last of the white plastic editions) and i've recently had troubles with the 7600GT Graphics card. The computer would get strange artifacts all over the screen, before crashing. Unfortunately, it is out of Applecare, so I took it into a shop and had the card replaced. Upon receiving it back, they told me that they replaced the graphics card, but still found problems with it booting up inconsistently. After some testing, they realised it was the Hard Drive controller at fault, and put my harddrive in an external USB enclosure and booted it off that instead. This was an easier solution than replacing the entire logic board, they told me. (and they gave me the enclosure for free). Now i've brought it home, and set it all up, only to find that the HDD fans are CONSTANTLY spinning at 5600 RPM, which is deafeningly loud, even so over my room fan. I presume this is because there is no longer any hard drive controller/hard drive in there. I've installed SMC Fan Control, but to my dismay you can only set the minimum fan speed, and not the max. If possible, i'd like to set the max fan speed at a much lower rate, without needing to open up the iMac. So my questions are: Is there a way I can set the max fanspeed for the HDD, or disable it since there isn't one in there anyway? And is there a better solution for booting my iMac OS onto an external HDD? (i.e. Should I look into buying a firewire 800 drive enclosure instead of this USB 2.0 one?) Many thanks.