HELP!! iMac 21,5 2011

[Asandul]

Friends, I need a help!

The video card (chip and memory) died - AMD Radeon HD 6750M 512 MB. iMac 21.5 2011

In my city (Ukraine, Dnipro) I found only a card - AMD Radeon HD 6770M 1 Gb, was on the Asus computer.

Question! Will it fit on my poppy and can I reflash the BIOS on the video card?

The documentation for my computer says that you can install AMD Radeon HD 6750M or Radeon HD 6770M 512 MB GDDR5.

I ask for your help. Attached screenshots.

 

[Nguyen Duc Hieu]

Different amount of RAM will cause the vBIOS file unusable.
Try the following Quadro cards (also taken out of old laptops) if you can find one cheaply.
K1000m
K610m
K1100m
K2100m

After getting your card, read the below post for at least 10 times, then draw out your repair plan and obtain necessary files also from that post.

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

 

[Asandul]

But will the computer work with this card? AMD Radeon HD 6770M 1Gb GDDR5 128 bit

 

[Nguyen Duc Hieu]

But will the computer work with this card? AMD Radeon HD 6770M 1Gb GDDR5 128 bit

No, it will not boot.

 

[Asandul]

Thanks!

 

[The_Croupier]

Friends, I need a help!

The video card (chip and memory) died - AMD Radeon HD 6750M 512 MB. iMac 21.5 2011

In my city (Ukraine, Dnipro) I found only a card - AMD Radeon HD 6770M 1 Gb, was on the Asus computer.

Question! Will it fit on my poppy and can I reflash the BIOS on the video card?

The documentation for my computer says that you can install AMD Radeon HD 6750M or Radeon HD 6770M 512 MB GDDR5.

I ask for your help. Attached screenshots.

Yes it is possible but not without a eeprom chip on the card and a modified vbios.

The card in your photo has the chip but its probably not 128kb so will not take the modified bios. You could inject the EFI part into the iMac’s bootrom using UEFITool as explained by Nick [D]vb

It's mentioned in the GPU upgrade thread that @Nguyen Duc Hieu linked.
Post in thread '2011 iMac Graphics Card Upgrade' https://forums.macrumors.com/threads/2011-imac-graphics-card-upgrade.1596614/post-27849973
Post in thread '2011 iMac Graphics Card Upgrade'
https://forums.macrumors.com/threads/2011-imac-graphics-card-upgrade.1596614/post-27851435

All going well I will be in Kyiv come September 9th 🙏

 

[jay508]

This red pcb is Dell M5950 HD6770M just vbios difference, storage chip capacity 64kb, direct refresh can be used iMac vbios need to replace the 128kb or 256Kb larger storage chip capacity can be.