[SOLVED] Obsolete iMac: help me to replace the graphic chip?

[bullosauro]

Hello everyone,
my iMac 2011 (21,5") has been considered "obsolete/vintage" from Apple and so they can not try to fix its problem. Its graphic card is an AMD Radeon 6750M and, in order to fix the problem of vertical lines and continuous reboot of the system, I should replace the graphic chip with a new one. After asking for a repair, to a non-official store, they asked me for 200$ intervention. Too much for me, too much for an old computer. So I would try to replace it from myself: can you suggest me a good tutorial/guide to do this?
Thanks and sorry for my english

 

[mjbn1977]

No my original comment but I found that on the web for you:
"The 21 inch screen iMac models always had their GPUs soldered to the logic board.
So, no way to swap out a GPU in these models.
The 2009-2011, 27 inch screen models have a socketed GPU Chip ( similar idea of the old ZIF socketed CPUs of older, more upgradeable Macs of the past). While the doing is difficult, you can only install a upgrade GPU that was one of the other GPU options offered for that iMac model year, only.
Finding these optional, higher VRAM GPUs will be very expensive to obtain and very difficult to install.
It will be very difficult replacement/upgrade if you are a complete newbie to doing computer system hardware upgrades and newbie to Macs."

 

[kanewolf]

Here is an iFixit teardown of a 21.5 iMac -- https://www.ifixit.com/Teardown/iMac+Intel+21.5-Inch+EMC+2428+Teardown/5485
I don't know if this is EXACTLY your model. But it does not look fun to teardown... Although iFixit gives it a 7 score.