Fix Your Stuff Community Store

Model A1311 / Mid 2011 / 2.5 & 2.7 GHz Core i5 or 2.8 GHz Core i7 Processor

432 Questions View all

Options

Led #3 off after GPU replacement

Hi all!

I am trying to upgrade my GPU with a Dell Nvidia GTX 770M. (VBIOS: 80.06.60.00.01)

on my iMac 21.5 Mid 2011 (EMC 2428).

After having installed the card, however, I do get a boot chime, fan spin, but I do not get Led 3 (and of course 4) lighting up (With the LCD mounted, no video is present).

Now, I need your help to work towards the correct direction, as I am not sure of what EXACTLY Led 3 indicates.

I know, as a general rule, that it indicates that “The Logic Board is communicating with the GPU”, although I would hope that you guys know a bit more precisely thant this, as:

  1. If the Led #3 lights up if ANY GPU is found, it either means:

a - That I have not connected it properly

b - That the GPU is broken

  1. If the Led #3 lights up only if the GPU is found AND working correctly, it could also mean:

c - That my GPU is not getting recognised, maybe because of a VBIOS problem (?) but it COULD be good.

Therefore, at the moment I do not know if:

1. My video-card is broken

or if

2. The issue lies somewhere else (like if I was sold the 770M from the incorrect manufacturer, which I really don’t think being the case, unless that eBay seller put a fake sticker on the card).

Of course, if I put back the default 6750M, Led #3 goes on without a problem, and I do get video with the LCD on.

Is anybody able to point me towards the right direction?

Thanks a lot for your help!

PS This is the card, just to make sure:

Block Image

Block Image

Answered! View the answer I have this problem too

Is this a good question?

Yes No
Score 0
Add a comment

2 Answers

Filter by:
Most Helpful Newest Oldest
Chosen Solution

Options

For ANYBODY experiencing this:

What happened was that even if the Dell VBIOS is supposed to work on iMacs, mine was for some reason not UEFI ready. It is not a big deal as it will be detected anyways from the motherboard, and most importantly from nvflash, which you’ll use to flash your GPU and make it UEFI-useable.

So, if you experienced this, follow these steps:

  1. Get yourself a 32GB USB or (preferrably) a hard drive/ssd that you can connect via USB.
  2. Using Disk Utility on Mac, erase it (Use Journaled FS)
  3. On a Windows Computer or virtual machine, download the software “WinToUSB” (you NEED the enterprise version)
  4. Using disk management on that Windows computer, select the primary partition of your external drive, and right click > Delete Volume
  5. On the erased space, right click > Create new simple volume
  6. Just go ahead with default options and make sure the file system is NTFS
  7. Download a Windows 10 ISO
  8. Open WinToUSB, select the ISO you’ve downloaded, next select your external hdd
  9. Choose Windows 10 PRO (IMPORTANT) when asked
  10. You wil be asked how to format the new hard drive. Select “Keep existing partitions”
  11. Select the already existing EFI partition as the EFI partition, and the NTFS (large one) partition as the second option
  12. Wait until the disk gets created
  13. Boot into that hard drive WITHOUT INTERNET (you may need another iMac or to put back the old GPU to do this)
  14. Setup Windows BUT do not connect internet.
  15. -> This matters as you do not want ANY drivers to be installed by Windows for now
  16. Do setup a password for the Windows account
  17. Open Windows Update preferences and opt to “pause the updates for a week”
  18. Open Remote Desktop settings and allow remote desktop connections.
  19. Rename your PC to something easy to remember
  20. Get another Windows PC, and connect your iMac (via LAN) and this PC to the same network (preferrably, make it a local only network by disconnecting the DSL cable from the router)
  21. On the Windows PC, open Remote Desktop and insert the computer name from step 18
  22. Get the nvflash utility with the ROM for your GPU by Nick[D]vB, i took mine from

die-oswalds.de/downloads/iMac.zip

  1. Now that you are in the iMac (remotely) use nvflash to flash your GPU with the corresponding ROM
  2. Reboot your system when asked, the Led #3 will appear on the motherboard. You can assemble everything back. You have a working iMac with an upgraded GPU, with a working Bootscreen! (for the brightness control you’ll need to download the Brightness Slider app).

Was this answer helpful?

Yes No
Score 1
Add a comment

Options

Ah! You fell into the trap!

You do realize Apples MXM boards have their own micro code. So unless you know how to flash the ROM as well as have the skills to program it you’ll get a black screen, loose the boot menu actions and brightness control (thats with a non-Apple AMD board).

You also realize Apple doesn't offer NVIDEA drivers for the GTX 770M board so you won't ever get the board to come up within macOS without patching it before you swap out the GPU board. The NVIDEA drivers Apple offers are limited to the boards the drivers where designed for, buggering them to work with your Nvidia GTX 770M is still a bit of a task.

To add to it, are you sure the board is even good?

Was this answer helpful?

Yes No
Score 0

2 Comments:

Thank you for your response Dan, however it was not what I was looking for.

For anybody experiecing my issue please read my own accepted answer, as I have solved the problem.

by

You only proved my point!

Its a chore, most people here are not as skilled as you are so my hats off to your doggedness to get it to work.

You still don't have boot options and the brightness control is not working.

by

Add a comment

Add your answer

vbios will be eternally grateful.
View Statistics:

Past 24 Hours: 0

Past 7 Days: 4

Past 30 Days: 17

All Time: 781