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2013 iMac Processor Conundrum

J

Jimbo_Mac

macrumors newbie
Original poster
Mar 15, 2020
8
0
UK
Hello Forum Members,

I'm looking for help to unravel a puzzle...

I'm in the market for a second hand iMac. I've been considering, evaluating and looking for a month or so now, and I've settled on a top-end (for the time) Late 2013 27" iMac with SSD (or Fusion), 32GB (but will settle for less), 4GB VRAM and the i7 3.5GHz processor. I believe that about summarises the highest custom spec on those machines at that time.

So, I think I have found one, at the price I set myself. I've been sent screenshots of the System Report. The report lists it as a iMac 14,2 model. It has the 4GB VRAM (Nvidia GTX 780M). It has 4 x 4GB RAM (for 16GB total), but that's fine for me. And it has 3TB Fusion Drive, so a 128GB SSD, which I'm good with. The concern that I am having is that the processor is listed as an i7 3.4GHz, rather than 3.5GHz. I believe i7 3.4GHz was the top end processor for the 2012 iMacs. The seller says that they bought it direct from Apple Refurbished store.

The processor details are: i7 3.4GHz, Processors: 1, Cores: 4, L2 Cache: 256 KB, L3 Cache: 8MB, Hyper Thread Technology: Enabled, Boot ROM version: 141.0.0.0.0, SMC version: 2.15f7. I've checked the serial number online, and it is listed as a Late 2013 iMac, but it doesn't confirm the processor type on that website.

I'm wondering if it is possible that at Late-2013 machine came with a 2012 processor? Is it even a 2012 processor, or could there be an error in the system report? Will it even make any difference to my day-to-day use of the machine (was there a significant improvement between these Intel processor types)?

Thanks in advance for anyone who contributes to this conundrum,

J
 
the terminal command

Code: 
sysctl -a | grep machdep.cpu.brand_string

may be informative.

For instance:
Code: 
Typhon:~ jeremy$ sysctl -a | grep machdep.cpu.brand_string
machdep.cpu.brand_string: Intel(R) Core(TM) i5-4690 CPU @ 3.50GHz

I don't know if you need to install extra libraries to use it though, and asking a novice user to run it may raise eyebrows, even though it's perfectly harmless. You're looking for a cpu model number i7-4771. A 2012 model imac will have a i7-3770. Or something different, if it's an i5, but then something would be very wrong, since a 4 core i5 doesn't have hyperthreading.

(technically, you can run
Code: 
sysctl -a
, and manually search the reams of text.)
 
Last edited:
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Thanks Jerwin. I may ask them to do this, although I too would have reservations about running a Terminal command someone on the internet sent me. Perhaps they would run the second shorter command, and send me the output in an email.
 
That's the problem though. I've seen the screen shots. It clearly says on the 'Hardware Overview':

Model Identifier: iMac 14,2
Processor Name: Intel Core i7
Processer Speed: 3.4 GHz
 
I've got a 2013 27" iMac with that processor and 24GBs of ram. I do a lot of photo editing in Lightroom, Photoshop and Luminar 4 and it handles all of that just fine. I don't do video. Maybe that will help you?
 
Thanks B.A.T. Can I confirm that you have an i7 3.4GHz processor in a 2013 iMac?

would you be willing to enter the command in Jerwin’s post above and let me the exact processor type?
 
Jimbo_Mac said:
That's the problem though. I've seen the screen shots. It clearly says on the 'Hardware Overview':

Model Identifier: iMac 14,2
Processor Name: Intel Core i7
Processer Speed: 3.4 GHz
Click to expand...
The application MacTracker (available on the Apple Store as a free download) show that model, 14,2 with 2 CPU options and the higher one is 3,4GHz. It also sjow higher speed CPUs so maybe those were optional at purchase?
 
Thanks Davidlv. I downloaded the app (very informative), and checked this model. The 3.4GHz mentioned is an i5. The machine that I am considering is an i7.

I'm left with the conclusion that it was sold from the refurbished store, either because it was an early demo model, that had the older processors, or that it was fitted with the wrong processor somehow, and was returned to Apple.

Thanks to everyone for their considered replies.
 
Jimbo_Mac said:
Thanks Davidlv. I downloaded the app (very informative), and checked this model. The 3.4GHz mentioned is an i5. The machine that I am considering is an i7.

I'm left with the conclusion that it was sold from the refurbished store, either because it was an early demo model, that had the older processors, or that it was fitted with the wrong processor somehow, and was returned to Apple.

Thanks to everyone for their considered replies.
Click to expand...
I suspect that someone may have swapped the CPU in the computer in question to the 3.4GHz i7 from a late 2012 model iMac. Regardless of whether or not it was ever in the refurbished store, it probably does have the i7 3.4GHz CPU as shown in that screen shot, and if it is a 3.4GHz from the 2012 line it is probably an Ivy Bridge CPU. The following year, the Haswell CPUs were introduced bringing about a 5% speed up. I used to have a late 2011 Sandy Bridge 2.4GHz MBP, and the Ivy Bridge CPU felt quite a bit stonger. Now I have the 2.9GHz i5 and coming from an old 4-core cMP model 4,1 at 2.66GHz, the iMac feels quite a bit faster. I think the 3.4GHz machine would be very usable, especially if it has 16GB or more of RAM. However, something is not right with the info, as it looks like a mix of the 2012 and 2013 models. Personally, I would stay clear of that machine, but it is your call.
The 13,2 iMac models (late 2012) used 2.9GHz i5, 3.2GHz i5, or 3.4GHz i7 CPUs, all Ivy Bridge. The late 2013 models used Haswell chips (about a 5% speed increase compared with the Ivy Bridge chips), i5 at 3.2GHz & 3.4GHz, or i7 at 3.5GHz. (all according to MacTracker).
Edit: Added some ideas and corrected a typo.
 
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davidlv said:
I suspect that someone swapped the CPU in the computer in question to the 3.4GHz i7. Regardless of whether or not it was ever in the refurbished store, it probably does have the i7 3.4GHz CPU as shown in that screen shot. I have the 2.9GHz i5 and coming from an old 4-core cMP model 4,1 at 2.66GHz, the iMac feels quite a bit faster. I think the 3.4GHz machine would be very usable, especially if it has 16GB or more of RAM. However, something is not right with the info, as it looks like a mix of the 2012 and 2013 models. Personally, I would stay clear of that machine, but it is your call.
The 13,2 late 2012 iMacs used 2.9GHz i5, 3.2GHz i5, or 3.4GHz i7 CPUs, all Ivy Bridge. The late 2013 models used Haswell chips, i5 at 3.2GHz, 3.4GHz, or i7 at 3.5GHz. (all according to MacTracker).
Click to expand...
Sound advice, and I agree with your conclusions. Thanks.
 
davidlv said:
I suspect that someone may have swapped the CPU in the computer in question to the 3.4GHz i7 from a late 2012 model iMac. Regardless of whether or not it was ever in the refurbished store, it probably does have the i7 3.4GHz CPU as shown in that screen shot, and if it is a 3.4GHz from the 2012 line it is probably an Ivy Bridge CPU. The following year, the Haswell CPUs were introduced bringing about a 5% speed up. I used to have a late 2011 Sandy Bridge 2.4GHz MBP, and the Ivy Bridge CPU felt quite a bit stonger. Now I have the 2.9GHz i5 and coming from an old 4-core cMP model 4,1 at 2.66GHz, the iMac feels quite a bit faster. I think the 3.4GHz machine would be very usable, especially if it has 16GB or more of RAM. However, something is not right with the info, as it looks like a mix of the 2012 and 2013 models. Personally, I would stay clear of that machine, but it is your call.
The 13,2 iMac models (late 2012) used 2.9GHz i5, 3.2GHz i5, or 3.4GHz i7 CPUs, all Ivy Bridge. The late 2013 models used Haswell chips (about a 5% speed increase compared with the Ivy Bridge chips), i5 at 3.2GHz & 3.4GHz, or i7 at 3.5GHz. (all according to MacTracker).
Edit: Added some ideas and corrected a typo.
Click to expand...
That shouldn't be possible. The Haswell CPUs in the late 2013 iMac models use a different socket than the Ivy Bridge CPUs used in the late 2012 iMac models. Haswell CPUs use the 1150 socket and Sandy Bridge/Ivy Bridge use the 1155 socket, hey are not pin compatible.

It most likely was upgraded by the end-user and is not the i7-4771 (3.5GHz) that was included as a CTO option on that model of iMac. I'd say that it is the i7-4770 (3.4GHz).
I've seen in previous threads, that people had success installing the i7-4770K in the iMac, so I'd imagine that the i7-4770 would also work fine.
From what I've seen the i7-4771 is not readily available aftermarket. The i7-4770 is much easier to find and is most likely cheaper because of that. The only difference between the i7-4771 and the i7-4770 is that the 4771 has a base clock of 3.5GHz vs the 3.4GHz on the 4770. Other than that they are exactly the same, including max turbo boost clock of 3.9GHz for both.

https://en.wikipedia.org/wiki/Haswell_(microarchitecture)#Desktop_processors

https://forums.macrumors.com/thread...-processor-in-late-2013-haswell-imac.1675201/
 
I agree with @smbu2000. Apple never sold a 3.4 GHz i7 iMac 14,2. I suspect a previous owner swapped the hitherto installed Core i5 CPU with an i7-4770 running at 3.4 GHz. If the price is right and the machine works I don't see a reason not to get it. You won't be able to tell the difference between a 3.4 and a 3.5 GHz processor.
 
Apologies for the delay in getting back to you all.

smbu2000, thank you. That was exactly the sort of technical depth I was after.

On balance, I've decided not to purchase this one. It may be that it was replaced by the original owner (although they are 'original' from the refurb store), but they deny this. It may be fine, but it may not, and the spec of the machine I am after is selling regularly on Ebay and FaceBook marketplace in the UK, so I'm under no pressure.
 
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