ATI 4850 for 27" imac in a 24" imac

[Soulcatcher]

A suggestion on a direction to go in would be welcome.

Early 24" 2009 iMac 9,1, Yosemite, 3.06 dual CPU.  Original GPU NVIDIA 130 GTX.  Acquired a 27" iMac 4850 GPU (661-5315).  This system could come w/ a 4850 (661-5135) GPU- both cards appear nearly identical in specs (prob. not the BIOS or drivers though.)  The NVIDIA is on the way out due to heat fatigue (no joy on the bake to fix attempt).  The new card is an Apple branded card.

 

SO.....Pulled NVIDIA, put in the 4850 designed for the 27" iMac (late 2009).  System boots no problem, all 4 LED's come on (so CPU recognizes GPU, GPU sending power to screen)....get a dark gray screen, dim backlighting- so screen is sort of working.  Tried this in SL before I upgraded OS, similar outcomes.  Tried some kexts and exotic patches in SL w/o luck (actually worse, 4th LED didn't light), so reverted to native, again before upgrade

 

1. I can remote into the system in either in Windows XP bootcamp (remote desktop) or via VPN when booting in OS X, see a screen/desktop, and remotely use the system...The card is id'd correctly in the system profile in both OS's, but in either Win or Yosemite I get no readable native display.  So I assume it's a card-display problem else I wouldn't be able to see the desktop images via remote?

2. All the extensions that seem to apply have the card's correct ID in them (1002-944a)

 

I'm thinking it's an issue with addressing the display's parameters. I have the specs on the 24" screen, product ID, Vendor ID etc, Device path, etc....

 LG:   LM240WU2-SLB4

Color LCD

Product ID 9C96   Product Code 0A- 9C,96

 

Any directional assistance would be welcome.  I would think the card change should work, and almost does natively... Attaching the profile of the new card below)

Thank you in advance!  (If I can get past this one hurdle, I'll be able to start on my first Hackintosh....)

 

 

 

 

 

[ameris_cyning]

Install Clover. You can use it on a real Mac.

 

Set InjectATI=true