iMac a1225 2008 nvidia quadro fx770m upgrade idea

[Roger(Apple)]

Hello, I have an iMac a1225 2008 3.06 GHz Ati Radeon 2600 pro hd 256MB. I would like to replace the graphics card in my iMac with Nvidia Quadro FX 770m 512MB, because I have such an unused card from an old HP laptop, as far as I know, everything is identical with Ati, RAM location, etc., so there are no contraindications to install it in the iMac. It would be very nice I liked this card because, first of all, I have such a card, secondly, nvidia 8800 gs is expensive and my Ati Radeon 2600 heatsink fits nvidia quadro fx 770m, the question is, would anyone be willing to help me and create a VBIOS for this nvidia, because it seems to me that after inserting Nvidia my iMac will not display anything, neither the start screen nor anything else. so if there was anyone who could help me with a quadro card idea I would be grateful. (I apologize in advance for my English 😅)

 

[Bigwaff]

Title says 2011 but relevant to 2008-2011 iMacs

2011 iMac Graphics Card Upgrade

iMac 2009 to 2011 MXM3 graphics card upgrade (Lastest update 10/13/2023 - this is the official documentation page - you found it finally!) This is the single and only documentation post. During the last years we constantly updated this post to reflect the lastet development of vBIOS and OCLP...

forums.macrumors.com

 

[Roger(Apple)]

Unfortunately, we are only talking about the 2009-2011 model, and the 2008 iMac 24" has the MXM2 graphics card type

 

[Nguyen Duc Hieu]

Unfortunately, we are only talking about the 2009-2011 model, and the 2008 iMac 24" has the MXM2 graphics card type

I would try the cards with LVDS vBIOS like Firepro M4000 or M5100. But it's adventurous and nothing can be guaranteed for your case.

IMAC-EFI-BOOT-SCREEN/EG at main · Ausdauersportler/IMAC-EFI-BOOT-SCREEN

How to create an EFI boot screen vBIOS for Apple Late 2009 to Mid 2011 iMac systems using AMD MXM graphics cards - Ausdauersportler/IMAC-EFI-BOOT-SCREEN

github.com

 

[JustPassing]

There are now much better MXM3 cards with Metal support for the iMac 9,1 > but only the older MXM2 cards will fit
the iMac 7,1 and 8,1 MXM2 slot, and no MXM2 cards support Metal. Some people tried these Quadro FX cards years ago,
I think there was a thread on the old Netkas forum, gone now but luckily I managed to find some of the iMac rom files.

The FX 770 probably didn't work because the LCD configuration is wrong, just showing a black screen or weird colors?
Also the video bios chip on the FX 770M card is only 64K, which is much too small to hold a full Mac EFI video bios.
You can try to flash this GT120 rom (same Nvidia G96 chip) but this rom file is missing the EFI part, so no boot screen,
and it might just totally break the FX 770M card if something does not match (memory types etc) - so I wouldn't risk it!

https://www.techpowerup.com/vgabios/167063/167063

But... There are two Quadro FX cards that can be flashed to work in these iMacs, both need the larger 8800GS heatsink.
You can flash the Quadro FX 2700M card with this patched GT130 rom, but these cards also only have a 64K rom chip,
so you would have to solder on a larger 256K chip. These cards were only used in a few laptops so are hard to find now.
Its G94 chip is not very fast but at least they will not overheat and fail like the faulty G92 on the original 8800GS card.

Probably the easier card to use is the Quadro FX 3600M, it has the same Nvidia G92 chip as the Apple 8800GS card,
but a newer revision that should not fail as quickly. They come with a 128KB bios chip that is just large enough to hold
the full 8800GS video bios with the EFI part, so they show boot screens and work in MacOS just like a real Apple card!

There were lots of FX 3600M cards available from Laptops and HP Proliant servers (fitted to Mezzanine MXM adapters)
Search HP part codes 580138-B21 / 490567-001 / 492189-001. Flash them with NVflash in windows, a linux boot disk,
or using a CH341A with a clip adapter on the EEPROM chip, see the iMac video card upgrade thread for flashing details.

The iMac vbios rom files are attached here, I hope they help save a few more old iMacs from the trash!