1. Slots 1 - Secure Digital (sdxc)
2. Secure Digital (sdxc) Slot Voice Recorder
3. Secure Digital (sdxc) Slot Machines

Apple Compatible iMac SDXC - SDHC - SD Cards

• A memory card’s capacity is determined by the file system being used to store data designated by the type of card. SD (secure digital) cards are the oldest, least used.
• SD cards will work in all host devices that support SD, SDHC, or SDXC SD High Capacity (SDHC™) card is an SD™ memory card based on the SDA 2.0 specification. SDHC capacities range from 4GB to 32GB Default Format: FAT32.

A Micro Secure Digital slot (MicroSD slot) is a small expansion slot located in mobile and other portable devices. It facilitates the increase of available memory via the insertion of a MicroSD card. MicroSD, MiniSD and SD are industry standard storage platforms governed by the Secure Digital Association (SD Association).

Aluminum Intel iMac SD Slot Location

Starting with the glass panel unibody aluminum iMac desktop computers, Apple started including an SDHC card slot on the right-hand side of the machines located just below the SuperDrive CD/DVD burner opening.
Later models revised the slot to support SDXC - (e)Xtended Capacity cards up to 1 Terabyte. So the model / year of your iMac system will determine if it’s SD and SDHC compatible, or if it’s a later model that also supports SDXC as well.

Slots 1 - Secure Digital (sdxc)

Slim Aluminum Retina iMac SDXC Slot Location

Apple continued to include an SDXC compliant, SDHC - SD backward compatible Secure Digital memory card slot on the slimmer aluminum iMac systems. This revision moved the slot the rear of the iMac alongside the audio, Gigabit ethernet, USB 3.0 and ThunderBolt ports instead of on the right-hand side of the display. The slot remains on the latest Thunderbolt 3 Retina iMac's as well.

Secure Digital (sdxc) Slot Voice Recorder

iMac SDXC Card	SDXC Card For iMacs	SDHC Card For iMac
SanDisk Extreme Pro SDXC Up To 95MBps Speed	PNY Elite SDXC Card Up To 90MBps Speed	Transcend Class 10 Up to 90MBps

Secure Digital (sdxc) Slot Machines

With the latest generation of Secure Digital flash memory SD cards at the high-end, we're seeing Read / Write speeds rivaling and outperforming conventional mechanical hard drives. So, not only has capacity increased but speed has increased greatly - though the data rates still fall far short of full-blown solid-state drives.