CPU Upgrade iMac Mid 2011

[Franzern23]

This is a Wiki post with information collected from the entire thread. Before you post, read this first.

The difference between Mid 2011 21.5" and 27" concerning CPU upgradability is mainly caused by the available power from the power supply.
--- The 21.5" has 210W power supply, the 27" has 310W.
As the power is shared among the components, it is recommended to
--- either use a CPU with TDP of 65W (or close to this) only for the 21.5"
--- or if you want to use a CPU with higher TDP, do it in the 21.5" unit only if you have a GPU with lower power dissipation, and have replaced the HDD with SSD, and have only 1 SSD in the system.
Using a HDD and/or multiple internal drives and a GPU with higher TDP might overload the supply so that the system runs unstable. If you experience unstable behaviour, reduce the internal power usage, or use a CPU with lower TDP.

Which CPU can be used:
1. Only CPUs supporting socket LGA 1155 can be used.
2. iMac 2011 officially supports only Sandy Bridge CPUs.
3. The XEON CPUs (Sandy Bridge = E3-12XXv1) are not officially supported but work mostly plug’n’play. Sleep is broken though for all Xeon models (i.e. with or without integrated GPU)
4. The "K" CPUs (e.g. i7-2600K) officially are not supported. The "K" CPUs allow overclocking, which is not implemented in the EFI and hence will not work. There is no incentive to use any of the "K" variants.
5. In principle the iMac’s Intel Z68 chipset is capable of handling Ivy Bridge CPUs which are also socket 1155. Unfortunately Ivy Bridge CPUs do NOT work yet, most likely due to missing CPU microcode in the NVRAM. First experiments of StephN999 and highvoltage12v by adding IvyBridge microcode to the NVRAM have yet been unsuccessful, so buying an IvyBridge CPU can not be recommended yet, apart from research (which is highly welcome)

The officially supported CPUs (of interest) are hence:

CPU	Base Clock / Turbo	Cores / Threads	TDP
i5-2400S	2.5 GHz / 3.3 GHz	4 / 4	65W
i5-2400	3.1 GHz / 3.4 GHz	4 / 4	95W
i5-2500S	2.7 Ghz / 3.7 GHz	4 / 4	65W
i5-2500	3.3 Ghz / 3.7 GHz	4 / 4	95W
i7-2600S	2.8 GHz / 3.8 GHz	4 / 8	65W
i7-2600	3.4 GHz / 3.8 GHz	4 / 8	95W

The community is interested in Intel's Sandy Bridge XEON (v1) CPUs, as they offer partially same or better performance at lower cost.
Also of interest is whether the iMacs 2011 can be made to operate with Ivy Bridge CPUs (newer generation, either i5/5 or Xeon) which would offer newer instruction sets and other improvements.

There is no evidence that Xeons with integrated GPU will be able to wake up from sleep. In contrast, there is evidence given by zabumbazarolha that Xeon 1275v1 has the same sleep issue.

The following CPUs are of interest:

CPU	Microarchitecture	Base Clock / Turbo	Cores / Threads	TDP
XEON 1260L	Sandy Bridge	2.4 GHz / 3.3 GHz	4 / 8	45W
XEON 1270 (w/o GPU)	Sandy Bridge	3.4 GHz / 3.8 GHz	4 / 8	80W
XEON 1275	Sandy Bridge	3.4 GHz / 3.8 GHz	4 / 8	95W
XEON 12xx v2	Ivy Brdge	see 12xx model	4 / 8	like 12xx model
i7-3770	Ivy Bridge	3.4 GHz / 3.9 GHz	4 / 8	77W
XEON 1275 v2	Ivy Bridge	3.5 GHz / 3.9 GHz	4 / 8	77W

The following results were achieved:

So far, only partial successes are reported. Sometimes, systems can't boot at all, sometimes can boot, but are unstable (kernel panic), or can't go to sleep or wake up.

---- Work in progress ---

Here is the progress on individual CPUs:

1. XEON 1270:
2. XEON 1260L:
3. XEON 1275 v1: plug and play in 2011 27“ imac, sleep is broken (zabumbazarolha)
4. XEON E3-1290v1: plug and play in 2011 27“ imac, sleep is broken (roscho)
5. i7-3770: does not work natively, research and testing in progress
6. XEON 1275 v2: does not work natively, research and testing in progress

(To be continued)


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Original post by Franzern23:
Hi All,

I am thinking to upgrade the CPU of my iMac Mid 2011 21.5 i5 2.5Ghz.
I mostly use the PC to watch Netflix as well as occasionaly playing online-games (League of Legends)

Do the below work and which would be the one with the strongest performance? The i7 or quad core i5?
I also heard only the 2600 version with 1155 work. Do both numbers need to be in line or does 1155 suffice? Do you have any other recommendation which is better?

thank you

Intel Sockel 1155 Core i7 Processor i7-2600 Box Prozessor (3400MHz, L2/L3-Cache) https://www.amazon.de/dp/B004FA8NLO/ref=cm_sw_r_cp_api_i_MZzLEbGH39WWQ)

Intel i7-3770 Core Prozessor der dritten Generation (3,4GHz, 8MB Cache, Sockel 1155, 77Watt) https://www.amazon.de/dp/B007RMH1WY/ref=cm_sw_r_cp_api_i_X8zLEb1TYWV53

Intel Core i5-3570 Prozessor (3,4GHz, Sockel 1155, 6MB Cache, 77 Watt) https://www.amazon.de/dp/B0083U94D8/ref=cm_sw_r_cp_api_i_u-zLEbTDVX1BN

Intel Quad Core Box Prozessor (Intel Core i5-2500K, 3,3GHz, 6MB Cache, 1155 Sockel) https://www.amazon.de/dp/B004FA8NX2/ref=cm_sw_r_cp_api_i_n.zLEbKJ1E41G

 

[nathan991]

none of those will work. The highest supported CPU for your unit is an i7 2600S. Make sure to get the S sku. It has a lower TDP the 21.5 inch iMacs require

 

[Franzern23]

Understood, made further research and have come across this one.
Is that the same CPU that apple used or is that an even more powerful than the strongest during release?
Thank You

Link

 

[smbu2000]

The i7-2600S was the upgrade option on the 2011 21” model.

https://everymac.com/systems/apple/...inch-aluminum-mid-2011-thunderbolt-specs.html

The 27” model used the higher TDP i7-2600.

I don’t think the 3000 series CPUs would be compatible even though the socket is compatible. On a PC motherboard they usually work fine with a BIOS update, but with iMac probably not.
The 3000 series CPUs were used in the late 2012 (thin) iMacs. My 2012 27” iMac hasthe i7-3770.

 

[Franzern23]

Ok, thanks. Is it worth it to upgrade the CPU or does SSD and RAM upgrade suffice?

 

[USB3foriMac]

SSD upgrade will give you biggest improvement.
If you worry about memory limit or CPU limit: check the Activity Monitor (in your Applications/Utilities folder). Check the CPU tab, if you see high percentage values frequently, an upgrade will improve speed (somewhat).
In the Memory tab, check the "Memory Pressure". This should be low values. If the value is frequently at the limit, you can add more RAM.
Adding RAM is easy.
Adding SSD is not so easy, but gives huge improvements.
Changing CPU is often less impactful. Changed an i5-2500 to i7-2600s, then benchmark shows improvement but from a work perspective there isn't much of a change.
[automerge]1586978103[/automerge]
And if the USB2 speed is bothering you: I just upgraded to USB3, and it's working great. Some hours effort for a fun DIY project. See the thread in this forum.

 

[Franzern23]

Great, thank you guys. Unfortunately, I broke the v sync cable and ordered a new one. Do you guys know if I can still use the Mac as many people report that the Mac is still Working with only some minor graphic errors. Does that damage my Mac since the cable is also connected to the temp sensor?

 

[USB3foriMac]

I personally do not believe that you could cause further damage. I would however try to repair the cable myself. despite small size of the connector(s), you can often repair things with patience, a magnifying glass, and a soldering iron.
I also harvest parts from other damaged electronic items, e.g. portable DVD players. They often have tiny connectors, too, which sometimes can be modified to be used in iMacs for the SSD or so, instead of buying expensive 3rd party cables.

Concerning temp sensor: if the sensor is disconnected, fans either spin up to max, or the machine does not boot. So if it boots, you are ok.
If you worry, you can monitor the temp with software such as Derman Fan Control: https://www.derman.com/Fan-Control?DEIredir or istat pro: https://bjango.com/mac/istatmenus/

For troubleshooting and repair, search for the "Apple Technician Guide iMac (21.5-inch, Mid 2011)" pdf. Sorry can't put a link as this is (C) Apple. Try Google or a torrent. It's also posted sometimes here in the forum as a link to Mega or so.

 

[Berenod]

Great, thank you guys. Unfortunately, I broke the v sync cable and ordered a new one. Do you guys know if I can still use the Mac as many people report that the Mac is still Working with only some minor graphic errors. Does that damage my Mac since the cable is also connected to the temp sensor?

The screen will most likely work without that cable attached.
However, chances are it will start flickering a bit, especially when you move your cursor around.

Can be a tad annoying, a bit like one of those high powerd lights in large warehouses with a broken ballast or something, you get some sort of faint flickering effect you can't really trace the source of!

Another often reported effect of not connecting that vsync cable is a high pitched whine, coming either from the display itself or the inverter board (where you normally plug in that vsync cable).

 

[Franzern23]

Understood, so I can use the Mac for now and get my back-up on the new attached SSD or shall I better wait till I get the replacement?

 

[Berenod]

Understood, so I can use the Mac for now and get my back-up on the new attached SSD or shall I better wait till I get the replacement?

Up to you as they say!
Never had a screen for a long time working without that cable, so not sure if it would cause any permanent damage...

I would wait for that new cable, just to be sure, if the screen goes whining, can't be good I would guess!

 

[rc3105]

I have an i7-2600 in a 21" 2011 and it works ok but it's right on the edge. The power supply doesn't have enough oomph left to spin up a regular 3.5 hd. With no 3.5 hd, dvd replaced by an ssd, and a K1100m video card it all works ok. (These changes all use less power than the original config.)

If I were going to do it again I'd go with the Xeon E 1220 ($20 on ebay) or 1230 which is almost as fast but only pulls 80 watts vs 93 for the i7-2600.

 

[nathan991]

I have an i7-2600 in a 21" 2011 and it works ok but it's right on the edge. The power supply doesn't have enough oomph left to spin up a regular 3.5 hd. With no 3.5 hd, dvd replaced by an ssd, and a K1100m video card it all works ok. (These changes all use less power than the original config.)

If I were going to do it again I'd go with the Xeon E 1220 ($20 on ebay) or 1230 which is almost as fast but only pulls 80 watts vs 93 for the i7-2600.

Wow...any kernel panic issues? I am thinking of swapping my i7-2600s with a Xeon E3 1270 (also 80W TDP)

 

[rc3105]

Not so far.

 

[StephN999]

Bonjour,

As promised to @>nathan991, I answered you here , on the other hand, no more hibernation the machine does not wake up...

If anyone has an idea or a solution?

Very happy with my Xeon E31270 anyway.

 Nom du modèle :    iMac
  Identifiant du modèle :    iMac12,1
  Nom du processeur :    Quad-Core Intel Core i5
  Vitesse du processeur :    3,4 GHz
  Nombre de processeurs :    1
  Nombre total de cœurs :    4
  Cache de niveau 2 (par cœur) :    256 Ko
  Cache de niveau 3 :    8 Mo
  Technologie Hyper-Threading :    Activé
  Mémoire :    16 Go
  Version de la ROM de démarrage :    87.0.0.0.0
  Version SMC (système) :    1.71f21

He is recognized as a Quad-Core Intel Core i5 by System Information, other software or even Windows normally see it.

Have a good day / evening.

edit: addition of information.

 

[highvoltage12v]

Bonjour,

As promised to @>nathan991, I answered you here , on the other hand, no more hibernation the machine does not wake up...

If anyone has an idea or a solution?

Very happy with my Xeon E31270 anyway.

 Nom du modèle :    iMac
  Identifiant du modèle :    iMac12,1
  Nom du processeur :    Quad-Core Intel Core i5
  Vitesse du processeur :    3,4 GHz
  Nombre de processeurs :    1
  Nombre total de cœurs :    4
  Cache de niveau 2 (par cœur) :    256 Ko
  Cache de niveau 3 :    8 Mo
  Technologie Hyper-Threading :    Activé
  Mémoire :    16 Go
  Version de la ROM de démarrage :    87.0.0.0.0
  Version SMC (système) :    1.71f21

He is recognized as a Quad-Core Intel Core i5 by System Information, other software or even Windows normally see it.

Have a good day / evening.

edit: addition of information.

Hello,
What copy of Mac OS? Can you please try a copy of High Sierra for me and let me know if sleep is broken still?

 

[StephN999]

Bonjour,
I have macOS Catalina,
No problems, thank you.

 

[StephN999]

Re,
tested with an external drive, I don't know if it matters?

Sleep is broken also, with and without OC Bootloader. 😢

 

[highvoltage12v]

Re,
tested with an external drive, I don't know if it matters?

Sleep is broken also, with and without OC Bootloader. 😢

Please try an older OS like High Sierra

 

[StephN999]

Bonjour,
I expressed myself badly, I tested on an external disk with High Sierra, on the other hand I do not know if it is necessary that I change / add Kexts, just for info, under catalina when it is added AppleIntelHD3000Graphics.kext is not not loaded, nor under High sierra or it is original.

thanks again,
Stéphane.

PS: I insist, I do not know if it works normally with an original external disk, I wanted a confirmation.

 

[StephN999]

Bonjour,
Many, many hours of research, a lot of tests of all kinds but I have not solved the problem of deep sleep.

I found and adapted a tutorial to change the type of microprocessor suddenly my system can see a Quad-Core Intel Xeon (On clover 0x05A5 "Hexadecimal", On OpenCore 1445 "Decimal)".

Informations matériel :

  Nom du modèle :    iMac
  Identifiant du modèle :    iMac12,1
  Nom du processeur :    Quad-Core Intel Xeon
  Vitesse du processeur :    3,4 GHz
  Nombre de processeurs :    1
  Nombre total de cœurs :    4
  Cache de niveau 2 (par cœur) :    256 Ko
  Cache de niveau 3 :    8 Mo
  Technologie Hyper-Threading :    Activé
  Mémoire :    16 Go
  Version de la ROM de démarrage :    87.0.0.0.0

 

[highvoltage12v]

Bonjour,
Many, many hours of research, a lot of tests of all kinds but I have not solved the problem of deep sleep.

I found and adapted a tutorial to change the type of microprocessor suddenly my system can see a Quad-Core Intel Xeon (On clover 0x05A5 "Hexadecimal", On OpenCore 1445 "Decimal)".

Informations matériel :

  Nom du modèle :    iMac
  Identifiant du modèle :    iMac12,1
  Nom du processeur :    Quad-Core Intel Xeon
  Vitesse du processeur :    3,4 GHz
  Nombre de processeurs :    1
  Nombre total de cœurs :    4
  Cache de niveau 2 (par cœur) :    256 Ko
  Cache de niveau 3 :    8 Mo
  Technologie Hyper-Threading :    Activé
  Mémoire :    16 Go
  Version de la ROM de démarrage :    87.0.0.0.0

View attachment 913089

Wait that's a 3.4GHz CPU in a 21.5" iMac? And it's an 80w CPU and it boots, I wonder if another 95W Xeon could book in the 21.5" iMac. Unfortunately I think the HD3000 Kexts needed to be loaded on boot for sleep to work.

 

[StephN999]

Bonjour,
I did not understand your first sentence, despite a French translation.

Otherwise I tested with HD3000 Kexts loaded with kextload and no sleep always.

Bonne journée/soirée.
Stéphane.

 

[StephN999]

Bonjour,
I did a lot of research on the UEFItool application, I saw that we could on the rom of the machine (at least on PC, but there's no reason for it to be otherwise on Mac) update the microcode of the CPU, I told myself that it would be interesting to do research on it, see even add support for the CPUs Ivy Bridge if the chipsets of the motherboard allow it of course.

As the iMac 2012 are compatible, we could recover some of the microcode CPU at once.

 

[highvoltage12v]

Bonjour,
I did a lot of research on the UEFItool application, I saw that we could on the rom of the machine (at least on PC, but there's no reason for it to be otherwise on Mac) update the microcode of the CPU, I told myself that it would be interesting to do research on it, see even add support for the CPUs Ivy Bridge if the chipsets of the motherboard allow it of course.

As the iMac 2012 are compatible, we could recover some of the microcode CPU at once.

i tried this a while ago for trying to make quad core (q8200s) CPU's boot on a 2009 iMac. I never got anywhere with it, the best I got was an iMac that would chime but no display. Maybe somehow there's a chance it will work with 2011 models? I'm leaning more towards no, I would have to find a really cheap iMac to experiment with this.