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DIY Bundle

and HDD Kit for 21.5" iMac (2012 and later)

Mac / USB 3.0
Mercury SSD and iMac HDD Kit
Everything You Need!
The complete solution for your 2012 and later 21.5" iMac
Experience the extreme performance of an OWC SSD upgrade with this easy DIY SSD and hard drive replacement kit. Add an SSD to your hard drive equipped iMac to experience faster booting, near instant application launches and data transfer speeds up over 500 MB/s.
Fast and reliable solid-state storage
Delivering the latest in flash NAND and controller technology, utilizing QLC and 3D NAND for long-lasting, power-efficient performance, the OWC Mercury 6G SSD line offer a powerful combination of performance and reliability for demanding everyday computer users.
A True DIY upgrade
This comprehensive kit has all the tools you need to replace your factory HDD with a high performance SSD, bringing a complete diy upgrade within your reach. Includes drivers, glass removal suction cups, and screen adhesive so you can get the job done yourself. The included OWC Express 2.5" USB 3.0 enclosure offers maximum mobile data storage/backup potential with a sleek, totally bus powered design. Just add your iMac's factory 2.5" hard drive or SSD and take your digital life with you wherever you roam!

Please note, that before attempting to perform this installation, it is recommended you watch the associated instructional video in its entirety to determine your ability to perform this complex procedure. OWC assumes no responsibility for damage that may occur during the install.

Release Candidate (RC) firmware set

There are two kinds of firmware for SSDs Mass Production (MP) and Release Candidate (RC). Prior to an MP firmware release, there are beta firmware releases and an RC firmware release. Often, the RC is the same as the MP release, however there can be small changes and bug fixes made between the two. OWC has evaluated the RC for the 6Gb/s SandForce 2281 Processor and found it to be stable with no issues reported during our testing. However, as with any evolutionary product, issues may surface as different usages and configurations are employed and it is important to understand that there will be further updates and revisions.

Since no firmware update is currently offered for the OWC Mercury EXTREME Pro 6G SSD, no update page exists. To see the typical steps involved with a self performed field firmware update, please visit our 3Gb/s product update page at: http://eshop.macsales.com/Customized_Pages/Framework.cfm?page=sf_firmware.html

It is important to note that the current firmware update tool requires the use of Windows XP/Vista/7. OWC is currently working on a Mac OS based update tool, but we do not have an exact availability date.

500GB Mercury Electra 6G SSD Specifications:


Phison PS3112-S12 with 3% over-provisioning
NAND Flash Components
Micron Synchronous Quad-Level Cell (QLC) 3D NAND Flash
Form Factor
Standard 7mm 2.5"
SATA 6.0 Gb/s
Capacity 1
466GB Useable Capacity
Total Flash Memory Components: 512GB
12GB Allocated to real-time data redundancy and error correction
Formatted Capacity1
466 GiB
RAID Support
SMART Attributes
Standard 2
Native Command Queuing
Up to 32 simultaneous commands
RoHS Compliant
Reach Certification


Height (max)
0.7 cm (0.3 in))
Width (max)
7.0 cm (2.8 in)
Length (max)
10.0 cm (3.9 in)


MTBF (Mean Time Between Failures)
1,600,000 hours
Secure Erase
Crypto Erase
Error Correction
Built-in ECC
TRIM Support
OS Dependent
50TB total bytes written (TBW), equal to 28 GB per day for 5 years
Nonrecoverable Read Errors
Less than 1 sector per 1016 bits read


Mac OS Compatibility
PC OS Compatibility
Other Requirements
Requires a Mac, PC, or drive enclosure with an available SATA drive bay. SATA III (6.0 Gb/s) required for best performance.


Sequential Read (Max)
Up to 525 MB/s
Sequential Write (Max)
Up to 516 MB/s
Sequential Read (Average)
514 MB/s
Sequential Write (Average)
509 MB/s


Write Mode (Max)
Up to 1.8 Watts
Seek Mode (Max)
Up to 1.8 Watts
Idle Mode (Max)
Up to 0.09 Watts

Environmental (Operating)

1500 G max at 0.5 ms
Temperature (°F)
32°F to 158°F
Temperature (°C)
0°C to 70°C
5% to 95% non-condensing

Environmental (Non-Operating)

1500 G max at 0.5 ms
Temperature (°F)
-40°F to 185°F
Temperature (°C)
-40°C to 85°C
0% to 93% non-condensing


Idle (Typical)
0.0 bels
Seek (Typical)
0.0 bels
  1. 1GB = 1,000,000,000 bytes. Total accessible capacity varies depending upon operating environment (typically 5-10% less). The actual total capacity will depend on your own defined file settings/preferences. 
  2. Temperature reporting is currently an unsupported feature because due to the operating characteristics of SSDs, it is highly unlikely one would ever exceed an OWC Mercury SSD's stated operating temperature ceiling of 158F/70C. However, we are looking into supporting this feature in the future via a firmware update. Firmware updates can be found here: http://eshop.macsales.com/tech_center/OWC/SSD.

Express Enclosure Specifications:

OWC Part Number

  • ES2.5BU3S

Software Requirements

  • OS
    • Mac OS 8.6 or later
    • OS X 10.2 or later
    • Windows 98 or later
  • Driver
    • Driver not required

Hardware Requirements

  • Minimum
    • Mac or PC featuring USB 1.1 interface
  • Recommended (Best Performance)
    • Mac or PC featuring USB 3.0 interface

Interface (Chipset)

  • (1) USB 3.0 (ASMedia ASM1053E)

Drives Supported

  • (1) 2.5" SATA 6Gb/s drives
    • SATA revision 3.0 (6Gb/s) compliant
    • Compatible with SATA revisions 2.0 (3Gb/s) and 1.0 (1.5Gb/s)

Power Supply

  • Bus Power via USB


  • Height: 0.6 in (1.5 cm)
  • Width: 3.1 in (7.9cm)
  • Length: 5.1 in (13.0 cm)


  • Without Drive: 2.0 oz (56 g)

Operating Environment

  • Dependent on mechanism installed
Manufacturer provided specifications for Other World Computing p/n K21IM12HE500 UPC#: 812437028713


Install Video

Note:Mercury Electra 6G SSDs can only be installed in 21.5-inch iMac models that came with a factory-installed HDD or Fusion drive. Solid-State Drive (SSD) only machines can be upgraded with an Aura Pro X2 SSD (Late 2013 - Current) or Aura 6G SSD (Late 2012 - Early 2013).
iMac Intel
iMac w/Retina 4K display
(21.5-inch Early 2019)
(March 2019)
Model ID:iMac19,2
3.6GHz i3, 3.0GHz i5, 3.2GHz i7
iMac Intel
iMac w/Retina 4K display
(21.5-inch Mid 2017)
(June 2017)
Model ID:iMac18,2
3.0GHz i5, 3.4GHz i5, 3.6GHz i7
iMac Intel
iMac (21.5-inch Mid 2017)
(June 2017)
Model ID:iMac18,1
2.3GHz i5
iMac Intel
iMac w/ Retina 4K display (21.5-inch Late 2015)
(October 2015)
Model ID:iMac16,2
3.1GHz i5, 3.3GHz i7
iMac Intel
iMac (21.5-inch Late 2015)
(October 2015)
Model ID:iMac16,1
1.6GHz i5, 2.8GHz i5
iMac Intel
iMac (21.5-inch Mid 2014)
(June 2014)
Model ID: iMac14,4
1.4GHz i5
iMac Intel
iMac (21.5-inch Late 2013)
(September 2013)
Model ID: iMac14,3
2.9GHz i5 or 3.1GHz i7
iMac Intel
iMac (21.5-inch Late 2013)
(September 2013)
Model ID: iMac14,1
2.7GHz i5
iMac Intel
iMac (21.5-inch Early 2013)
(March 2013)
Model ID: iMac13,1
3.3GHz i3
iMac Intel
iMac (21.5-inch Late 2012)
(October 2012)
Model ID: iMac13,1
2.7GHz i5 , 2.9GHz i5, 3.1GHz i7


  • (1) OWC Mercury Electra 6G SSD
  • (1) OWC Express enclosure - black
  • (2) OWC 2-1/4" Suction Cup
  • (1) Torx T10 driver
  • (1) 21.5" iMac Adhesive tape set for proper display resealing
  • (1) Nylon Pry Tool (Spudger)
  • (1) OWC Screen Removal Tool
  • (1) OWC Blue Microfiber Screen Cleaning Cloth

NOTE: This kit contains consumable and/or one time use components and therefore is non-refundable if opened. If you have any concerns about your ability to perform the upgrade, you can return the unopened kit for a refund.


The best warranty is one you never have to use - but should the need occur - we're proud to provide a superior level of support and service coverage to our customers.

3 Year OWC SSD Limited Warranty

1 Year OWC Enclosure Limited Warranty

Even when not used, we understand the peace of mind afforded by a longer warranty period. OWC's industry leading coverage is a testament to our confidence in the reliability of the solutions that we offer. OWC solutions are engineered to demanding quality standards in order to deliver the most reliable, highest performance available on the market in each storage category.

Customer Ratings

Write a Review 4.8 / 5 16 out of 16 (100%) reviewers would recommend this product
1 2 3
Verified Buyer
Reviewer: mrbilky Location: Philadelphia PA Age: 45-54 Experience Level: Power User Owned Product: over 6 months
Rating: 5/5 Excellent service, top notch instructions! December 4, 2016 My iMac became painfully slow boot up and getting the spinning ball of death all the time watched the video on this installation it was very intuitive and took the plunge my iMac is like new and very snappy - tripled my read/write speeds, don't be afraid of this upgrade very easy took 20 minutes and most of that was peeling off the old adhesive. Oh and don't panic if you misplace a strip or two of new adhesive the kit provides extras!

This review is from DIY Kit for 2012 or later 21.5" iMac's factory HDD: 480GB OWC Mercury Electra 6G SSD.. Customer Videos:

Verified Buyer
Reviewer: enplaned Location: Ithaca, NY Age: 45-54 Experience Level: Home User Owned Product: 1-3 months
Rating: 4/5 Worked like a charm September 6, 2016 Successfully upgraded HDD to an SSD in my parents' iMac, radically improving its speed/response. OWC made it do-able, if not exactly easy. Watched the videos many,many times, and took great care at all times and it all worked out. It is not for the faint of heart, but it was less of a big deal than I expected.

They will get another five years out of the iMac, I bet.

I would recommend this item to a friend! This review is from DIY Kit for 2012 or later 21.5" iMac's factory HDD: 240GB OWC Mercury Electra 6G SSD.. Customer Videos:

Verified Buyer
Reviewer: Anonymous Location: Texas Age: Over 65 Experience Level: Home User Owned Product: 1-3 months
Rating: 5/5 Great SSD July 8, 2016 My factory installed hard drive began to fail on my iMac after only two years. After viewing the OWC video on replacing it, I decided to try to replace it. Everything worked as advertised and now I have an iMac that is working better than ever.

Having a 1Tb internal hard drive fail has caused me to keep all important files on an external drive and backup everything.

I would recommend this item to a friend! This review is from DIY Kit for 2012 or later 21.5" iMac's factory HDD: 240GB OWC Mercury Electra 6G SSD..

DIY Bundle 500GB
and HDD Kit for 21.5" iMac (2012 and later) Mfr P/N: K21IM12HE500 OWC SKU: OWCK21IM12HE500 Complete DIY kit for upgrading your late 2012 or later 21.5" iMac's hard drive 3 Year OWC Limited Warranty Ships: Same Day Only $129.90Bundle Priced for $102.75
Add to CartOther World Computing K21IM12HE500 In Stock, Click to Buy Now
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