First of all, i tried to do a lot of searching but comes up empty handed. Before anyone try to post "You can't upgrade iMac's graphics card" or "iMacs graphics card are soldered!", let me make this clear, aluminum iMacs (20", 21.5", 24", 27") uses MXM slots, its just unclear whether the lower end models like the one uses 9400M has it. Since 9400M is soldered on the logic board. Heres my question. 1. Does the 21" low end 2009 iMac (iMac10,1 the one that has Core 2 Duo with Nvidia 9400M) has an empty MXM slot? 2. Is the logic board of iMac10,1 (low end, 9400M) identical to iMac 10,2? The one that has AMD Radeon HD 4670. 3. Does the HIGH END 2009 iMac (iMac10,2) has 9400M? 4. If yes, then generally AMD HD 6770M (Found in 2011 iMacs) will work with the low end 10,1 iMac right? Cuz it works for 10,2. Thanks!