Indeed. After 5 years the original GPU developed some kind of intermittent flaw so I swapped it out with the board (and cooler) from a mid-2010 iMac. It's an

Indeed. After 5 years the original GPU developed some kind of intermittent flaw so I swapped it out with the board (and cooler) from a mid-2010 iMac. It's an easy swap. Mac OS X identifies it as a Radeon 5750 but Windows calls it a 5850. Either way, I believe it's very similar in performance to the original 4850 that was the top spec in the late-2009 iMac.