Putting a 680MX into a 27" 2011 iMac?

[omvs]

I read about some people upgrading the GPU on a 21" 2011 iMac. (ex: this thread https://forums.macrumors.com/threads/1596614/)

I have a 27" 2011 iMac that I tried doing the same thing, but couldn't get the machine to boot when I swapped in the card. While trying some experiments, I ended up breaking the LCD data cable, decided I was pushing my luck, and said the heck with it.

But since I've been unable to ebay the card for a reasonable price, I'm debating giving this another shot. Has anyone managed to accomplish this on a 27" iMac? I'm also curious if its possible to get the bootscreen video, or if I'll have to blindly do the filevault password or disk selection...

EDIT: Whoops - I meant using a 680M, not a 680MX....

 

[wmy5]

I see in the post you mentioned in your first paragraph, the MXM card must be EFI-supported, so it's probably because your card only support BIOS that your machine won't boot. Maybe you can try the same card as the author of that thread?

 

[omvs]

I gave it another shot tonight. Only 2 of the 4 LED's lit on the mainboard with the 680M. From what I can tell, LED #3 comes on when the GPU is succesfully engaged, so I'm guessing either the card I got is bad, or somehow the firmware doesn't support the 680M I got. Either way, seems like I'm screwed - it never even tried to boot off the hard drive.

 

[joe-h2o]

You need a card that is EFI capable.

You can flash some cards to have this, but a standard card designed for a Windows box won't work.

Some PC cards with non-EFI roms will work in the Mac Pro, but not show the boot screen during power up. It sounds like the iMac's self test is detecting the lack of EFI video card (from its perspective, the card is failing the test) and simply refusing to boot. The Mac Pro, on the other hand, boots with the video card "broken" (until it initialises later and starts working).

I think your only option at this point is to find a card flashed with the Mac-ready EFI rom. I know some people who do this sort of thing have been asking for people with 2012 iMacs to dump this rom from Windows, but I'm not sure how successful this effort has been.

Either way, the only way that card you have is going to boot if if you install it in a windows machine and flash it.

 

[ajaysthinkin]

I read about some people upgrading the GPU on a 21" 2011 iMac. (ex: this thread https://forums.macrumors.com/threads/1596614/)

I have a 27" 2011 iMac that I tried doing the same thing, but couldn't get the machine to boot when I swapped in the card. While trying some experiments, I ended up breaking the LCD data cable, decided I was pushing my luck, and said the heck with it.


EDIT: Whoops - I meant using a 680M, not a 680MX....

Whats the status as of now?

 

[omvs]

Whats the status as of now?

Never got anywhere - still have the 680M sitting in a anti-static bag. I think its a UEFI problem, but without access to a PC laptop with a MXM slot I don't see any way I can get it to work.