Chosen Solution
Hi I found out my iMac 21.5 late 2009 apparently had 2 graphic cards in it. A dormant nvidia 9400 integrated graphics in the logic board and a removable Radeon HD 4670 (on a mxm card). Having in mind I had to 2 Gpus I took out the Radeon HD 4670 for another computer in need of a graphics card, but now the iMac screen doesn’t come up although I can hear everything working in the background. Is there a way to activate the nvidia 9400 that is integrated in the logicboard? Even if I have to put the other gpu back in to set this up (then removed it - as to the first idea)? Other iMacs run only with nvidia 9400 (the standard one). How can I ask the iMac to use this one as the default one instead? Many thanks.
There were three configurations of this machine and we need to know with one you have. However the on board video acts like a pre-amp. You still have to have the amp. Video Card: GeForce 9400M* VRAM Type: Integrated* Details: There are two configurations of this model – MB950LL/A, which has a NVIDIA GeForce 9400M graphics processor that shares memory with the system and MC413LL/A, which has an ATI Radeon HD 4670 with 256 MB of dedicated GDDR3 memory. UPDATE 9/14/17 A lot of would be very interested in seeing if you can get this to work. You could potentially save hundreds of thousand of Mac from the dump if you can. So please keep us updated. I would do the research on this but I have been out of the office for 5 days at the iFixit un-conference and am swapped with students starting school. But try this discussion and let us know if it is a resolution: https://apple.stackexchange.com/question… @danj could be a solution on the 2011 MBP with the bad GPUs
Update (09/17/2019)
May be the reason THESE RESISTOR OPTIONS SELECT BETWEEN MCP AND MXM TO DRIVE THE INTERNAL DISPLAY IG-ONLY O-OHM RESISTORS NEED TO BE PLACED AT THE MXM CONNECTOR TO AVOID STUBS WE WILL ROUTE FROM MCP TO THE 0-OHM RESISTORS, THEN ON THROUGH MXM TO THE LCD CONNECTOR IF THIS ROUTING IS NOT FEASIBLE, MXM ALIASES WILL BE REPLACED WITH ADDITIONAL 0-OHM RESISTORS
Would someone have a schematic for this board. According to the information here, Its a case of swapping over some 0 ohm restistors from the MXM lines to the IG lines. There are a couple of pullup 1K & 1.7K resistors that need to be moved too. It looks doable. If someone can share the 820-2494-A schematic (already have the board view) then I will be able to create a guide on how to get the 9400 working and driving the display. There also may be resistors on the external DisplayPort lines that may need to be swapped also.
