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iM 4,1-14,4 iMac 2011 (see more) UEFI Firmware Mod
- Thread starter StephN999
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Ended also doing EnableGOPPatched
All Working without issue
Thinking about trying EnableGOP ... this looks more complex - will save that for the weekend
Great work! @m0bil
View attachment 2243023
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Nice!Ended also doing EnableGOP - Attached my final rom file - use at your own risk
Take into account your published rom file contains iMac serial number and logic board serial number (they are used by Apple for iCloud/iMessage/Facetime authentication), and also may contain some bluetooth/wifi pairings in the nvram part.
How did you brick it ? and why can't you flash backup with CH341a ??
I tried to insert EnableGop. When I flashed back the mod, I saw that I can't verify the flash. After that no chime, no boot, only 2 leds. I have tried another computers, software and OS's to flash back the original firmware, but all fail (I can erase, flash, but can't verify), no boot. Now I have doubts that the dump is OK. Even if I took it two times and the size it was the same. Solutions?
Please post your dump so I can have a look at it.
I could also give you the EnableGOP-VBIOS I'm using for my own RX480 - provided you aren't one of those who needed a different VBIOS than the "normal" one...
Your CH341a might have difficulties to get a good connection to the EEPROM; you could try the screwdriver trick I've used quite a couple of times for recovering; you need to short circuit the upper middle two pins from powering on until the boot process begins (obviously you need to boot into Windows or Linux in order to be able to reflash - although there's also the possibility to flash using an EFI version of amdvbflash).
Hey man! I ****ed up the Mac firmware, not RX480 (I can flash it easily with ch341a). I tried to insert EnableGop in the iMac with EnableGop_1.4.ffs/UEFITool.app. My iMac doesn't boot even with original GC. And for sure if I unbrick it, I want your RX480 firmware. Thank you!
That's really sad.
I know that @Jazzzny has recently been recovering an iMac firmware EEPROM - he might be able to help you.
Send me the bios of your 480 video card. I will make you a normal 480 bios.
Thank you! But my problem isn't RX480, it is the iMac EEPROM and the modality to flash it back.
Send me your iMac bios.
Jazzny will take a look.
And I'll take a look.
Now you press the power button for 15 seconds, do not release the button. You should hear a long beep. This is the process of resetting and restoring the firmware from stock.
Then turn off the network for 1 minute. And turn it on again!
Write this latest BIOS to your Mac. After that I will send you a BIOS with EnableGop enabled. https://disk.yandex.ru/d/VgfT3FpHG-mbIw
Which brand/model is your eeprom chip ?? Some 2010 iMacs have SST eeprom chips that can be a pain with CH341a...
If you can't _verify_ the flash, then you really haven't flashed at all (and should avoid rebooting in that state... 😥). You've erased (by the sound of it), but the new flash attempt hasn't worked.
You may already be aware, but verification failing here is nothing to do with the contents of the ROM (is it a valid ROM or not?), it's to do with whether the setup (hardware (if any), software) which you are using to flash is working correctly, i.e. to do with whether flashing the data - any data - is working or not.
If you previously managed to take a dump with the same size and contents (`diff` the two versions and get no difference output) twice, it sounds as if there is hope that it may be usable. But it also sounds like you have an unbootable machine right now, and may need to buy and learn to use a CH341A USB hardware programmer plus SOIC clip (to attach to the NVRAM chip), in order to re-flash.