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tanker5

macrumors member
Original poster
Apr 19, 2011
95
3
Hoboken
Has anyone successfully tried to upgrade the CPU in a 2011 21.5" iMac? Mine was shipped with an i5 2400s CPU. I was thinking of upgrading it to an i7 2600s (which is the processor that shipped with the build to order 2011 iMacs).

However, after doing some research, I found out that the ivy bridge processors and sandy bridge processors use the same CPU socket. So, in theory, the 3770s should be compatible with the 2011 iMac logic board. The two processors are roughly the same price, so I think the 3770s is the way to go -- more performance for my money. It also uses about the same wattage as the 2400s and 2600s, so there should not be a power issue.

I know there might be some drivers that might need updating. In the 10.7.4 update, OS X added support for ivy bridge processors and HD 4000 graphics. So, IF OS X can be run successfully after upgrading the CPU to the 3770s, I believe that as long as the computer is at least running 10.7.4 (which added support for ivy bridge processors) it should be fine. Since my iMac is currently running 10.8.3, all of the required drivers should be built into the OS.

Oh -- and I am fully aware that this would void the warranty. The computer is over 1 year old now, and since I do not have AppleCare, there is no warranty anymore on it.

If anyone out there has any suggestions for me, or any reason they believe I'm wrong, please let me know. I'll reply in the next few days after I make my decision on what I'm going to do. Any help is greatly appreciated.
 
What about the compatibility of the support chipset in your iMac and the processor you are looking at? Also if it is compatible, will OS X work with that combination.
 
What about the compatibility of the support chipset in your iMac and the processor you are looking at? Also if it is compatible, will OS X work with that combination.

I believe that the chipsets are compatible. But I can't find a definite answer online, just conflicting reports. However, I think any hardware compatibility issues would be fixed by the updates in OS X 10.7.4 and later.

There might only be one way to find out for sure though...
 
Well the Sandy to Sandy upgrades seems absolutely pointless. There isn't an appreciable difference between the models used in the 21.5" models. If one isn't up to the task, you are likely to be unsatisfied with the other. The ivy one you quoted is still a jump of 12W maximum tdp, and I'm not sure how hot one runs compared to the other in actual use, or if the board firmware works properly. The 3770 would give you an increase in performance if you are currently cpu bound. These things are often more commonly upgraded with mac pros because of the stratification within the E/EP cpus and greater year to year consistency between chipsets. For a lot of people the proposed upgrade wouldn't extend the useful life of that machine by one day. If it's lagging on something I understand. Otherwise it may not be worthwhile unless something cpu bound is a bit laggy today. With most of these things you won't know if it will work properly (without kernel panics or other issues) until you try it.
 
Well the Sandy to Sandy upgrades seems absolutely pointless. There isn't an appreciable difference between the models used in the 21.5" models. If one isn't up to the task, you are likely to be unsatisfied with the other. The ivy one you quoted is still a jump of 12W maximum tdp, and I'm not sure how hot one runs compared to the other in actual use, or if the board firmware works properly. The 3770 would give you an increase in performance if you are currently cpu bound. These things are often more commonly upgraded with mac pros because of the stratification within the E/EP cpus and greater year to year consistency between chipsets. For a lot of people the proposed upgrade wouldn't extend the useful life of that machine by one day. If it's lagging on something I understand. Otherwise it may not be worthwhile unless something cpu bound is a bit laggy today. With most of these things you won't know if it will work properly (without kernel panics or other issues) until you try it.

It's true that there is not much of a difference between the i7 2600s and the i7 3770s. BUT -- Since my iMac currently has the i5 2500s (by the way - earlier in the post I accidentally stated that the current CPU is the 2400s - It's the 2500s), either the 2600s or 3770s would be a noticeable performance upgrade.

The 3770s has the same wattage as the 2600s (65 watts). the 3770 and 3770k are 12 watts higher.

Even the 2500s to the 2600s would be worthwhile to me because I would be going from a quad core i5 to a quad core i7 with hyper threading (8 virtual cores clocked at 2.8 GHz vs 4 cores at 2.7 GHz).

The i7 3770s is selling for around $300, while the 2600s is selling for about $330. So, the 3770s seems like a better deal because it's cheaper and has higher benchmarks.

Also, the Ivy Bridge processors support the z68 chipset which is the chipset on the 2011 iMac logic boards.

If it's possible to get the performance of a 2012 iMac with my 2011 iMac, I think it would be a worthwhile upgrade.
 
I believe that the chipsets are compatible. But I can't find a definite answer online, just conflicting reports. However, I think any hardware compatibility issues would be fixed by the updates in OS X 10.7.4 and later.

There might only be one way to find out for sure though...
OS X may not support the combination. Remember, if it's something Apple doesn't sell they haven't tested against that combination, so they would not fix issues around it. Apple already has enough systems they need to test OS X with.
 
Please post your results, I've very interested in this-- have been contemplating the same process.
 
Please post your results, I've very interested in this-- have been contemplating the same process.

Well, I've decided to give it a shot and see what happens. I'm prepared to suffer the consequences if I don't succeed. I have the 3770s on order and it should be here later on in the week. Unfortunately, because of my hectic work schedule, I might not have a chance to sit down and do the swap for another week or so. I will keep you posted on my progress.
 
Well, I've decided to give it a shot and see what happens. I'm prepared to suffer the consequences if I don't succeed. I have the 3770s on order and it should be here later on in the week. Unfortunately, because of my hectic work schedule, I might not have a chance to sit down and do the swap for another week or so. I will keep you posted on my progress.

Can't wait :D
 
Update -- i7 3770s NOT compatible

Well, I have been going at this all day. I have dis-assembled and reassembled my 2011 21.5" iMac about a dozen times. I have gone through almost 2 full tubes of thermal paste. No matter what I do, the computer will not boot with the Ivy Bridge processor. It's not a total loss though. I learned a lot about the internal components of the iMac, and was able to also install dual SSDs in a RAID 0 configuration (thanks to OWC's special kits for replacing the HDD temperature sensor cable in the 2011 iMac and adding a second drive to the 2011 iMac -- Links below). I plan on using the ivy bridge processor I purchased for a hackintosh build. All in all, I look at it as a learning experience. My computer is back up and running with the original 2500s cpu. I plan on swapping it out with a 2600s eventually.

OWC kit for replacing original HD in a 2011 iMac:

http://eshop.macsales.com/item/Other World Computing/DIYIM21HDD11/

OWC kit for adding a second drive in the 2011 iMac:

http://eshop.macsales.com/item/OWC/DIYIM21SSD11/
 


Thanks for your perseverance but sorry it didn't work.

The reason is that it requires EFI BIOS, or whatever the Mac equivalent is of BIOS.

I tried to upgrade a Gigabte z68 chipset ATX motherboard with a 2500k to a 3550 CPU and it wouldn't boot with the IvyBridge CPU. Put the 2500k back in, boot's no problem. The GigaByte's board can be updated to EFI BIOS but I tried that without success. The socket is the same for 2nd and 3rd gen Intel CPU's (LGA1155), but it's just the EFI bit that's needed.

Looks like my 2011 iMac is staying with the 2500s CPU...

Hope this helps.
 
I realize that the last post here was 2 years ago, and the last before that over 4 years ago...but this Ivy Bridge upgrade is exactly what I was hoping to do. Have there been any revelations or workarounds or "asterisks" to the "it won't work" conclusion? I have a specific reason to want to do this...

My father has a 2011 iMac 21.5" 2.5GHz (i5-2400S) system. I have recently purchased a Phantom 3 Pro drone and a Panasonic G85 mirrorless camera, so I've been shooting a fair bit of stuff in 4K H.264 that I want to share w/ him w/o having to transcode just for him to view the raw stuff. Apparently the Sandy Bridge Quick Sync capabilities top out at 1080P for decode/playback (Reference), so while CPU utilization for 4K playback is better on his machine now under 10.12 Sierra than it was under 10.6 Snow Leopard, it's still a bit choppy because it's using software instead of Quick Sync (and it's not lighting up all 4 cores).

Ivy Bridge, OTOH, has improvements to QS to support 4K playback, best I can tell (unfortunately I don't recall where I found that). So, since the socket is the same, and since the next year model 2012s come with Ivy Bridge CPUs, I was hopeful to try one similar to what shipped in those 2012s. Okay, what I grabbed on eBay is slightly different: i5-3475S, which is the same 2.9GHz as the i5-3470S of two 2012 configs, but with HD Graphics 4000 instead of 2500. Only after I've ordered this CPU do I come across some definitively negative conclusions like this one. :(

Anyway, as you can see I have a specific use case where the CPU generational upgrade would be quite useful to me. But unless there's been some "a-ha" moment in the last 4 years, it sounds like it's not going to be worth the effort...

Thx,
Fred
 
Didn't have any expectations, but tested the Ivy Bridge i5-3475S in an available spare 2011 iMac 27" last night anyway...no dice. Powers up but no POST/chime. Rats. I think Hackerwayne on another thread here completely lied about his "success". Not sure why one would be such a DB and confuse the issue like that, but there it is. Screenshots are inconsistent and/or fakes anyway...

Really wish I could accomplish this one task (4K playback) w/o an entirely new machine. :(
 
With a Mac make sure any CPU you use is used in another Mac. Not saying they wont work but chances are slim. The limitation is imposed by CPU (including its microcode) and Apples logic board compatibility. Intel CPU's from broadwell and newer will work in a Hackintosh.
 
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Circling back around on this...nothing new to report, and I gave that Ivy Bridge i5-3475S mentioned above a new home in a 2012 iMac instead. It was a modest, but welcome, clock speed boost to the machine, which I had open to install an SSD blade into anyway.

BUT, after lots of firmware discussion, analysis, and general wizardry over in the Mac Pro forum lately, led by @tsialex, it got me to thinking: might a similar firmware tweak on a 2011 machine be possible to allow an otherwise seemingly compatible Ivy Bridge CPU upgrade to run? Hoping that Alex, being tagged, might have a look here and advise whether such a thing might be doable. :)
 
Circling back around on this...nothing new to report, and I gave that Ivy Bridge i5-3475S mentioned above a new home in a 2012 iMac instead. It was a modest, but welcome, clock speed boost to the machine, which I had open to install an SSD blade into anyway.

BUT, after lots of firmware discussion, analysis, and general wizardry over in the Mac Pro forum lately, led by @tsialex, it got me to thinking: might a similar firmware tweak on a 2011 machine be possible to allow an otherwise seemingly compatible Ivy Bridge CPU upgrade to run? Hoping that Alex, being tagged, might have a look here and advise whether such a thing might be doable. :)
Some initialisation is made by the microcode and some by code into the BootROM, microcode is simple to add remove, but the other part like ACPI tables, integrated GPU and etc, is not. I don't know about this iMac to say what is needed.
 
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