upgrade videocard Radeon HD 4850 on Radeon HD 6970 2 GB RAM?

the connectors are the same.

But the HD 6970 has a much bigger heatsink with 3 heat pipes(the 4850 and 5750 have only 2 heatpipes) and might not fit in a iMac 2010 model. It also means it produces more heat and has a higher tdp of 75 watts. I can't find the tdp of the 4850 but the mobility 5xxx series doesn't go higher then 50 watts so i expect that will be the same for the 4xxx series.

iMac's 2010 and 2011 use the same power supply's so the higher tdp might not be the problem.

I've heard Apple uses a custom firmware on its gpu models so 3'party graphic cards won't work.

This means the system checks what graphic card is installed and might also check what model number is installed and reject the different model. But this doesn't have to be the case

Maybe it only checks if a Apple firmware gpu is installed and it might work fine.

Just make sure you can return the HD6970 if it doesn't.

Good luck and let me know if you succeed.

I just upgraded my late 2009 iMac 27" (iMac11,1) replacing the HD4850 with HD6970 yesterday.

I did have to cut out the plastic bezel underneath the video card as shown in the iFixit guide where there are a bunch of cable, to allow the card to slide underneath the PCB into the connector.

Connecting the heat sensor of the video card is a pain. And after the install in iStat the GPU die temp does not show up. however since i am controlling the fans manually I am not to worried (i still have GPU heatsink info and all the other temped indicators)

I bought the HD6970 from macpremiumparts on ebay. They were great, fast shipping to Australia. The card works great!!!

Hello, does your card HD6970 in replacement of HD4850 still work on your Imac 27 late 2009. Mine crashed and if it works I would appreciate if it does work. You can’t find or hardly an HD4850 today. thanks for your answer