Imac late 2013 27 inch 4790k possible with efi mod?

[Sebasboy]

From my research, the 27 inch late 2013 imac can boot with max a 4771 i7 cpu,

a 4790k would result in a no post, this is likely a firmware limitation (maybe deliberate?)

The imac 2014 shipped with a 4790k as an option,


anyone know if it could be possible that the EFI just needs some microcode added or some patches?

 

[blufrog]

IIRC CPU support depends on the SMC. Not sure if it can be updated or not.

 

[Sebasboy]

IIRC CPU support depends on the SMC. Not sure if it can be updated or not.

I am tempted to just grab a cheap 4790k for testing,

comparing the 2 biosses, there is a few changes here and there for init for intel stuff,

the bios chip is easily enough accesible without logic board removal so i can fire off some test firmwares,


i am working on an custom vbios so the chip has to come off anyway XD


maybe with some luck with enough cursed BS we can get a 4790k working,

also i am not promising anything but maybe i can get the cpu overclocked under mac os too,



windows is easy enough with throttle stop. i think a 4770k does work on the imac as it's a 2013 chip too,


But it will be a very scuffed implementation....

 

[mmomega]

This exact model I can not be sure right now, but I have upgraded 2 other iMacs that came with i5's up to the highest i7's of there particular era and they worked flawlessly, everything on the chip works, it shows proper naming in about this Mac and more info.
I also have that 4771 iMac and will check if it was one that I upgraded.
but I had gotten eBay very in-expensive CPU's that straight worked. I did not have to patch anything, I chose to just do fresh installs of the latest OS that could be installed on those machines via USB drive installer.

 

[Sebasboy]

This exact model I can not be sure right now, but I have upgraded 2 other iMacs that came with i5's up to the highest i7's of there particular era and they worked flawlessly, everything on the chip works, it shows proper naming in about this Mac and more info.
I also have that 4771 iMac and will check if it was one that I upgraded.
but I had gotten eBay very in-expensive CPU's that straight worked. I did not have to patch anything, I chose to just do fresh installs of the latest OS that could be installed on those machines via USB drive installer.

aye, i don't know if the cpu actually does not work myself,

but i came across a lot of posts from people sying their 4790k will not post in the 2013,

something bout only 2 of the lights lighting up and nothing else,

i think all 2013 cpu's will work in this (tbh maybe some xeon's could be fun)

but the 2014's don't post,

 

[Sebasboy]

There ya go, got the 4790k working on a 27 inch late 2013 imac, after all these years of people saying it cannot be done or have not looked at potential firmware mods,

i copied the ME firmware + CpuPei from the 27 inch 2014 to the 2013's bios dump and that's pretty much it,