if your mac is running pc3-8500 ddr 3 then you should not put pc2-6400 ddr 2. its not the same ram. open up your imac and look at the ram to see what it is. the faster ram will run at a slower clock speed but not vice versa.
kingston says for early 2009 imac 24 you can put in 8 gigs but you should check your Mfgr's System P/N's then you will know for sure. I've used kingston value ram in all my macs. they worked well as long the clock speed and voltage was the same.
if your mac is running pc3-8500 ddr 3 then you should not put pc2-6400 ddr 2. its not the same ram. open up your imac and look at the ram to see what it is. the faster ram will run at a slower clock speed but not vice versa.
kingston says for early 2009 imac 24 you can put in 8 gigs but you should check your Mfgr's System P/N's then you will know for sure. I've used kingston value ram in all my macs. they worked well as long the clock speed and voltage was the same.
http://www.ec.kingston.com/ecom/configurator_new/modelsinfo.asp?SysID=54755&mfr=Apple&model=iMac+Intel+Core+2+Duo+20&search_type=&root=uk&LinkBack=http://www.kingston.com/ukroot&Sys=54755-Apple-iMac+Intel+Core+2+Duo+20-inch/24-inch+(Early+2009)&distributor=0&submit1=Search