hard driveimacssdupgrade
I have got an iMac (EMC 2638) here, with 1TB hard drive. I have read that there is a PCIe SSD slot on those iMacs as well, originally for the fusion drive. Is it possible to upgrade my iMac with such a SSD module? I don't care if it would work as a fusion drive, or simply have it as the main drive for OS and programs.
If this is possible, where can I buy such a SSD module? iFixit has repair instructions, but maybe I can let this be done by my local Mac shop.
The PCIe flash storage will be faster than the SSD, but how much you'll notice that in the real world is questionable.
The PCIe card used in the new iMacs is the same (custom) stick-like form factor Apple uses in their other products.
You should get the 1TB or 3TB Fusion drive configuration if you want more than 256GB of storage and don't want a larger SSD. You could of course get an external USB3 drive to provide large storage if you prefer, or even get a USB/Thunderbolt external SSD.
The $200 for the fusion drive is expensive, but not insanely so. It will give the most noticeable performance boost of any possible upgrade on the iMac, unless you prefer to spend the money doing an all-SSD setup, which will still be very, very fast.
You're not going to find a compatible PCIe SSD for any less than Apple's upgrade cost. For example, OWC sells compatible SSDs for the MacBook Airs (http://eshop.macsales.com/shop/SSD/OWC/Aura_Pro_Air_2012) that may work, but I don't believe anyone has specifically tested it.
I will also note that opening up the current iMacs is more difficult than in the past, due to the laminating process on the screen to reduce glare, parallax and weight. It would be a false economy to buy a $2000+ computer, only to risk damaging it by opening it up for the chance to save $50. If external storage is not desirable and you want more capacity, go Fusion.
From the page you linked -
The initial production of the base model for the 21.5" iMac didn't come with a slot for the SSD. Later production models included the SSD slot, but there's no way to determine if the 2012 21.5" iMac with a 2.7GHz processor has the SSD slot without opening it up to see if it's available. If you have already opened the iMac up and it does have an SSD slot, this SSD is compatible.
The 2.9 & 3.1 GHz machines should be compatible.
Best Answer
It seems there is a workaround for this. One can buy an external Thunderbolt SSD, and set up a Fusion Drive. Since Thunderbolt is extremely fast, this is a low cost, low work solution that is very suitable for desktop machines like the iMac.
There are a lot of guides online on how to set up the disks.
It boils down to
Maybe one can skip the install to external HD, since newer Macs come with Internet Recovery. This would save quite a bit of work.
Once in recovery, you can see your disks using
diskutil list. Let's say you see the disks disk1s2 (internal HD, OS X partition) and disk2 (clean SDD).Now you can create the Fusion Drive:
The output of the first command results in a UUID which you use in the second command.
After this, you should be able re-install or restore OS X onto the Fusion Drive.
I haven't tried this yet, it is merely a summary of the linked article! So be careful and make backups!