2011 iMac 27″ GPU failure Fix/Upgrade

Posted on by josh Posted in repair

After coming across a 2011 27″ iMac with a bad GPU (graphics card), I embarked on the Google search for a fix. Most people either buy used parted out iMac AMD video cards or reflow their existing cards (bake the card in an oven at 400 degrees for 8 mins). This reflow usually works, but eventually most people report the card fails again and has to be reflowed again.

I wanted to get something that wasn’t a used ticking failure waiting to happen (apparently all these AMD cards made during these years had faulty chips/solder). I came across this thread that inspired me to try a GTX 765 ( https://forums.macrumors.com/threads/2011-imac-graphics-card-upgrade.1596614/ )

So far it works, but with some caveats.

  • No Apple boot screen.
  • Cant get to recovery or option boot menu. *(was able to boot from an external disk via Firewire and USB using the Startup Disk section in SysPrefs)
  • Brightness control doesn’t work and you need a program to now control this. (Shades)
  • Only one of the thunderbolt ports works for using an external monitor.
  • Cant monitor GPU die temp.
  • No Target Display Mode

*In the future, Ill see if I can get my hands on a reasonably priced GTX 1060m to test

AMD Radeon HD 6970M 1GB VS. Nvidia GTX 765M
Nvidia GTX 765M with X bracket shaved to avoid capacitors
Heat Sink also had to be shaved to make room for different layout of chips.
Thermal paste and pads I used
iMac with new GPU and SSD installed SSD bracket file can be found here https://www.thingiverse.com/thing:2594636
iMac up and Running
Card shows up great
External monitor test on the one working thunderbolt port
Before and after-from idle to streaming 4 open windows with 1080p videos streaming at once. Our house is also around 80 degrees at this time.
Streaming a chat on Google Hangouts.