iMac 2011 Sandy Bridge to Ivy Bridge!?


I would like to run an Ivy Bridge processor on my 2011 iMac (Sandy Bridge)

I changed the microcode without any problem (in duplicate on my machine and I imagine on many other PC/Mac machines according to my research)

My machine won’t start despite this change.

I figured there must be something else to change, so I looked at the firmware of the upper machine (iMac 2012) and saw that it had a lot of CPU related stuff, among others CPUINITDXE, which I copied and replaced without any result.

Please let me know if I missed something.

With my thanks.

With my best regards,


Not my field regarding if possible or not or what needed for modded iMac firmware (besides mCODE), but Apple logicboards
sometimes do not accept processors with different TDP values, that differs from the original included.

Chipset? Model? Intel ME 8 needed and bios itself needs to be ME8/ IVB capable and the latter is (very) difficult to check.


Thank you for your answers.

@MeatWar > I don’t think there are any particular problems with TDP, several Xeon Sandy Bridges (so not really original CPUs for this machine) have been tested and work natively too, just that on the 21’5" model the power supply is not powerful enough.

@lfb6 > it’s Z68, the models are all 2011 iMac.
I’ve never used Intel ME 8 so answer the question…

On imac-2011-see-more-uefi-firmware-mod on macrumors forum, we provide the roms of 2 machines 21"5 and 27" which are not used anymore (I specify it because each firmware has a unique number).

I’m still researching, modifying and testing, if anyone has any informations, advice, I’m obviously interested.

Thanks again!

ME is part of the firmware/ROM


Thank you again, if you have any leads even if I must admit that it is quite complex at my level…

I asked a question on a topic about macpro (can’t leave a link yet.) in order to get more leads, it’s really far from being simple on this side too.

It’s become more than a challenge for me, I’m sorry it’s so complicated for me, sorry if I’m bothering you…

Humm… as expected, its ME7 (SandyBridge)



Thanks again for the answers.

What’s wrong that it’s ME7, it’s not possible to upgrade to a higher version?

I’m not giving up on the idea, but I’m clearly not up to doing this on my own…

Generally not…unless the manufacturer had released fw updates with higher ME as we saw in some PC motherboards, but i don’t recall seeing Apple released old ME7 to 8 updates.
Even so, apart from ME there is some work to do with CPU mCodes, research about recovering from bad fw flash, identifying the correct SPI chip, a flash programmer maybe…
Keep looking around…macrumors, insanelymac, etc

It’s not just ME and µcode.

- Different bios modules need to be updated, and dependency isn’t that easy to check. Possible modules for example CpuDxe, CpuInitDxe, PchInitDxe, PowerManagement, Setup, MemoryInit, CpuInitPei …

- Possibly bios modules need to be updated to work with ME8.

Maybe possible to flash a bios from an IVB- mac and see what’s happening, but I’d assume macs do check for hardware before booting?

Bad ideia FW from IVY mac, do not recommend, my opinion only.


Thank you again for your answers, enclosed is a firmware for a 21.5" iMac 2011 and a firmware update for a 21.5" iMac 2012 (different structure as it is an update file)

If it can shed some light on the difference in structure between Sandy Bridge and Ivy Bridge.

copy of one of my message on macrumors: "I changed CpuInitDxe, CpuIoDxe, PeiCore, CpuInitPei, the machine seems to reboot (still no beep), I put back my old microprocessor and my original firmware to reassure myself, everything works! phew!"

Have a nice day. (3.98 MB) (3.51 MB)


I’ve done a tour of the firmware there:

Microcode 153D2197-29BD-44DC-AC59-887F70E41A6B x2
PeiCore x2
PeiCpuIoPei x2
CpuInitPei x2
MemoryInit x2
PchInitPeim x2
S3ResumePei x2
CpuS3Pei x2

I just installed Ubuntu and I'll see what I can do with CoreBoot.
It would be nice even if at worst it would only allow booting on Linux.

Edit: CoreBoot test KO

IME 7 to IME 8 OK not tested!



It’s not much, but after a lot of testing of different versions of IME, my last test with the last IME 7 “Slim” allows the machine to boot normally,
I don’t know if it’s good news for my future research though, but I wanted to point it out…

Have a nice day.

Edit: Just a question, if the original IME is a SKU Slim, if we use another version of the SKU it won’t work?