Imac 2011 – GPU issue
Is your iMac 2011 working? is it too hot? You are so lucky. But you need to keep it cooler otherwise you will have the same problem as me. One day you might see that it’s not booting and you see some stripes in the screen. If you see that, that means your GPU (graphic card) is failed.
It’s could be an easy/cheap fix if you can buy a used part on eBay. My original card is HD 6970M 2GB, it’s still now almost $200 on eBay. So I finally have to use an older card , it’s about $40. It’s 6770M 512MB. It’s originally for IMac 21in, but it works well in my 27in 2011. There are a lot of guides on the internet showing how to disassemble your iMac, it’s quite easy, but you need a special tool to take the front glass off.
The next part is how to keep the machine not too hot, I found a software name “Macs Fan Control” , it’s free. It allows you to set your iMac fan speed, I put them at always at 2200rpm , it’s a little bit noisy, but not too much. You also can display the current temperature on the top menu bar. My Mac is now mostly running under 52oC, I don’t feel the heat behind the machine.