iMac 27 mid 2011 No Boot

[Mb175]

Hello, my iMac 27 mid 2011 does not boot anymore.
Black screen, no chime but the hdd spins up as well as the fans.
The device also beeps if I remove the ram, so I suppose the logic board works.
A good year ago I already took out the graphic card once because i had issues with it.

I already removed the lcd, diagnostic led 501 (first one from the left side) as well as 502 light up.

503 doesn’t light up, chances are high it’s the graphics card again am I right?
In addition I want to ask if somebody is aware of such issues caused by a bad graphics card ?
Because last time my card went bad I still had a chime.
Thanks very much in advance for possible answers.

 

[Nguyen Duc Hieu]

Hello, my iMac 27 mid 2011 does not boot anymore.
Black screen, no chime but the hdd spins up as well as the fans.
The device also beeps if I remove the ram, so I suppose the logic board works.
A good year ago I already took out the graphic card once because i had issues with it.

I already removed the lcd, diagnostic led 501 (first one from the left side) as well as 502 light up.

503 doesn’t light up, chances are high it’s the graphics card again am I right?
In addition I want to ask if somebody is aware of such issues caused by a bad graphics card ?
Because last time my card went bad I still had a chime.
Thanks very much in advance for possible answers.

If only 2 LEDs are lit up, and the 3rd is not, the it's definitely a GPU issue.
4rd LED is about the internal LCD.

 

[Mb175]

Yes the Problem was caused by the GPU, yesterday i took it out of the system cleaned all the thermal-paste from it and baked it in a normal oven at 200°C for 11 minutes. Now it works again all LEDs light up and my iMac boots fine again.

 

[dondrapersf]

Yes the Problem was caused by the GPU, yesterday i took it out of the system cleaned all the thermal-paste from it and baked it in a normal oven at 200°C for 11 minutes. Now it works again all LEDs light up and my iMac boots fine again.

you baked it for 11 minutes ?

 

[Mb175]

you baked it for 11 minutes ?

Yes i baked the graphics card for around 11 minutes at 200 - 215 degree Celsius.

 

[Mb175]

you baked it for 11 minutes ?

If you need further informations. For example how to bake and what you should take a look at to prepare. Just ask.