2011 21.5 iMac upgrades

If you are intent on keeping this one, an SSD is the only cost-effective and performance-effective path. It is not an easy upgrade but doable at home if you are careful. Believe me, the reward will be great without messing with your CPU or GPU.

If your slowness is in starting the computer and opening apps, but everything is fine once the app is running, that is a classic symptom of a slow hard drive, not a CPU, GPU, or RAM issue.

I have a direct comparison of what an SSD does. I have an entry-level MacBook Pro with a 2.5ghz i5 dual-core 3210M processor. We also have a 2011 iMac with a 2.5 ghz quad-core i5 2400S. As shipped both had slow SATA 3GB/sec mech drives connected to a fast SATA 6G/sec drive bus. The iMac's quad processor and discreet graphics made it a little faster than the MacBook Pro.

Both were slow to start up and to launch apps but ran OK once an app was running. The 7200 rpm drive in the iMac scored about 90-110MB/sec in read/write scores; the MacBook Pro's paltry 5400rpm drive struggled to make 70MB/sec. After adding an inexpensive 6GB/sec SSD from Other World Computing to the MacBook Pro, its drive scores are now 500MB/sec. That is close to a 10X data transfer boost. Although the MBP still has a less capable processor, in actual use it is now a pleasure, while the iMac with its old-school mech drive is a royal pain.

To show how that translates into the real world, here are launch times for my two slowest-launching apps on my MacBook Pro 2.5ghz as shipped; after doubling the RAM; and after the SSD upgrade:

Base system as shipped:

4GB RAM and slow SATA 3GBps 5400rpm hard drive: MS Word and Photoshop Elements took 15-18 seconds to be ready to use.

First upgrade, doubling the RAM:

8GB RAM and slow SATA 3GBps 5400rpm hard drive: MS Word and Photoshop Elements took 15-18 seconds to be ready to use.

Second upgrade, inexpensive solid-state drive

8GB RAM and fast SATA 6GBps SSD: MS Word and Photoshop Elements take 3-4 seconds to be ready to use.

Comment: ""Cost effective" is that, when the 2011 dies or is shifted on, you can remove the nice SSD, put it in an external enclosure and continue to use it as a backup or expansion drive for a newer computer.

Our 2011 is also a great computer but Mrs AJ uses it for our tax software and, next year, that software will no longer run on High Sierra, the max OS for that model. So we will have to go shopping regardless of what I put in her iMac today.

If I decide to experiment with an SSD in the 2011, I will be getting this "kit," That is important because anytime you replace the HDD in a 2011 iMac, you must install a special thermal sensor cable to keep the cooling fans from running at full sped all the time. The kit includes that cable:

https://eshop.macsales.com/item/OWC/KITIM11HE500/

If you buy a new iMac. do whatever is necessary to have the funds for the factory SSD, not the mech drive or the Fusion option.

Hot rodding a 2011 iMac. I guess that is as good a hobby as any. Good job with the RAM and SSD upgrade. Everyone else has already covered the practical (which is to buy a new mac) so on to the impractical technical possibilities...

iFixit has CPU/GPU hardware replacement guides (rated at maximum difficulty).

Your CPU choices are limited by power, cooling, and what the logic board bios knows about. The i7-2600s works because that is the same CPU Apple shipped as the top custom configuration. I don't know anything about Xeon options, but ignore any advise to go over 65W as dangerously out of spec.

The GPU is more complicated. You are restricted to MXM-A by power/size limits, but then further restricted by OS drivers and firmware. Have you heard about Mac Pro users flashing PC cards for bootscreen support? Same principle, except that a compatible VBIOS is also required for the iMac's internal display to work correctly.

Without flashing you have basically just one option: a 6770m made for an Apple iMac. With flashing (extra hardware required) any radeon 6770m. Working 3rd party vbios have been customized for the Quadro K1100M/K2100m, but I haven't heard of any other Radeon options.

FWIW, you are literally going to perform open heart surgery on

a patient with little life left anyway.

CPU replacements are always an iffy thing on Macs that you

can actually swap CPUs on. More often than not, people have

done this sort of work and ended up with a lot of money spent

and an iBrick. Basically because of the total lack of firmware

and hardware support for alternate devices.

Bottomline, by the time you have spent all the money and effort

to accomplish this, you would have had a sizable down payment

for a new iMac, and Apple Refurb iMac, or a later model refurb

from some of the reputable refurb Mac suppliers.

Also, consider, you are spending a bunch of money on a computer

with snail slow USB2, slow WiFi, and an old version of Thunderbolt

that will have a difficult time try to find new devices for.

In addition, come the release of macOS Big Sur, the newest your

version of High Sierra (if you are even running) will no longer

be supported with security updates.

If you want more performance, rather than spending any time, effort and money on a 10 year old computer with little value and well past it's prime it is more wise to spend your resources on a replacement Mac. Just consider it, I also have a 2011 iMac, yes I'm typing on it now but it's soon to go into the recycle bin.

I totally agree with everything you stated, woodmeister50.

This Poster is wasting a lot of efforts, time and money on a nearly 10-year old iMac.

This Poster would be better off with a newer iMac model with more modern specs.

Here are the specs of yours

https://everymac.com/systems/apple/imac/specs/imac-core-i5-2.5-21-inch-aluminum-mid-2011-thunderbolt-specs.html

As far as I know, you cannot upgrade the cpu or gpu.

First, have you considered the obvious on just buying a new iMac or Mac Mini? I replaced my 2011 with a 2018 mini, and with the 2020 storage bump the value on those has only gotten better. The 2019 iMacs are pretty good too once you opt for an SSD.

Second if you are determined to upgrade start with an HDD to SSD upgrade if you haven't already.

Third, the HD 6770M probably isn't worth the time/cost/effort/risk. I want to say it only offers +20% performance. You are also correct that the 6970M will not work. The 21.5" is only designed to power/cool 55W MXM-A and will not work with higher power MXM-B cards like the 6970M.

As already mentioned, please do consider purchasing a new one. A 9 year old computer can have its logic board or graphics card/screen fail at any time (aside from the spinning drive) - all electronics will fail at some point; some sooner and some later. 9 years is a very good run; I'd retire it instead of throwing money at old technology for an upgrade. if you do decide to go for a new one: 16 GB of RAM and an all SSD would be ideal if you can do it. Shy away from fusion drives as they have a very small SSD portion and the major drive is still a very slow spinning drive.

I still use and run a late 2009, iMac as my daily driver!

My wife uses a 2010 iMac.

We will continue to use these until something catastrophic actually happens to them.

We are both still running the last Mac OS X El Capitan update 10.11.6!

I still use OS X 10.9.5 Mavericks as my preferred Mac OS version.

None of the newer Mac OSes are compatible with most of my older, legacy software and offer NO extra new and cool features that I can use on such an old iMac.

For many newer Mac OS features, I rely on still supported third party alternatives to AirDrop and AirPlay and Continuity and Handoff.

These iMacs will need to die before I spend another chunk of cash to replace them!