If you look at the manuals, there is a separate manual for the 2.53Ghz. Curiously, I went to compare the manual for the 2.53Ghz MBP and the manuals for the other two 15 inchers. Look like there's only 1 fan on the 2.53Ghz 15" MBP? Manual for 2.53GHz MBP: http://manuals.info.apple.com/en_US/MacBook_Pro_15inch_2.53GHz_Mid2009.pdf Manual for the other 2 MBP: http://manuals.info.apple.com/en_US/MacBook_Pro_15inch_Mid2009.pdf On both manuals, page 39 will show you the internal of the MBPs. Is there only 1 fan on the 2.53Ghz model because there's no dedicated graphics?