1T was the largest drive available in the late 2011. These usually have a WD Black and those drives are past end of life. Not one of my clients still has one installed. These were great drives but generate a lot of heat and the iMac is an oven.

The late 2011 is my favorite. FW and Thunderbolt, USB 2, and was th first year of the SATA III 6G bus (for the drive only—the optical is on a 3G bus). The 27” has a spare SATA bus that yours doesn’t—not an issue now that 2T and 4T SSDs exist. My wife has one.

High Sierra installs fine but the HHD cannot be formatted APFS. It makes a difference on some drive intensive applications such as Digital Performer but not the huge difference that going to an SSD will. APFS was optionalonly during the beta period so I was abl to test it both ways.

It’s possible that if your drive was replaced, it already has the OWC heat sensor. In that case, you only need the SSD and bracket. If not, you need the 2011-on sensor.

Besides the huge speed and performance boost, an SSD reduces the internal heat.

A Micron 1100 is the same drive as the Crucial MX300. It is only sold to systems integrators and OEMs and has a 90 day warranty (their cost takes this into account). SIs sell these on eBay, sometimes at great prices.

TRIM is part of the Mac OS but disabled on 3rd party SSDs by default. After installing an SSD, run the following in Terminal: sudo trimforce enable. Click through the Apple CYA warnings.

Disable App Nap globally. Many apps do not play well with it. It’s sole purpose is to preserve battery life—not an issue with an iMac.

Disable App Nap

BIAB 2025 Audiophile Mac
24Core/60CoreGPU M2 MacStudioUltra/8TB/192GB Sequoia, M1 MBAir, 2012 MBP
Digital Performer11, LogicPro, Finale27/Dorico/Encore/SmartScorePro64/Notion6 /Overture5