2009 iMac 27” won’t boot past the loading screen

[Sebfromottawa]

Sorry I didn't notice that.
In that case, your GPU has probably dead. Very basic function like boot screen at low resolution still work. Just when the driver is loaded and heavier tasks require the GPU to accelerate, the defects kick in and stop the machine (internal short circuit or trigger the thermal, etc)
I did experience that myself. A short-circuit WX4150 just bricked the whole machine.

Darn that's a shame but makes more sense because it couldn't be a dead ssd since I was still able to boot into safe mode. must be the gpu

 

[Nguyen Duc Hieu]

Darn that's a shame but makes more sense because it couldn't be a dead ssd since I was still able to boot into safe mode. must be the gpu

I just bought an iMac 27" late 2009 today.
When fully cooled down, it would boot to desktop and do simple tasks such as opening text only web pages, copy files, etc.
Just when I try to do something with graphic accelerated like watching Youtube videos, it freezes.
This is a clear sight of a dead GPU, which is easy to fix.