820-2494-A 661-5420 Logic Board MXM - Late 2009 A1311, 3.33GHz iMac, 21.5 inch NB-3128W
This is a replacement 3.33GHz logic board for the 21.5-inch iMac. There are two different types. One (661-5306) is for the model with integrated graphics and the other (661-5420) is for the model with the discrete ATI video card.
EEE code: 9RW
Apple part number: 661-5420, 820-2494-A
Compatible models: A1311-Late 2009-MB950LL-MC413LL, 820-2494-A
Compatible Mac info. : 21.5-inch 3.06GHz iMac, 820-2494-A
661-5420 Logic Board MXM - Late 2009 A1311, 3.33GHz iMac, 21.5 inch 8202494A