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Green rectangular circuit board with gold edge connectors and black memory chips, 204-pin SODIMM form factor

A-Tech

A-Tech 4GB DDR3 1866MHz SODIMM 204-Pin memory upgrade for iMac 27 Late 2015

SKU CH-7S0Z-6X9QC

A 4GB DDR3L 1866MHz SODIMM module for upgrading compatible 27-inch iMac models from late 2015

  • Total capacity4 GB
  • Rated speedDDR3L 1866 (PC3L 14900)
  • ChipsetMajor Brand Chipset
  • Rated voltage1.35 V
  • Buffer typeUnbuffered
  • Memory rank1Rx8
  • 4GB capacity expands multitasking headroom for Late 2015 iMac
  • 1866 MHz DDR3L speed matches factory PC3-14900 spec
  • 35 V low-voltage operation reduces heat in slim chassis
  • 204-pin SODIMM form factor fits Apple iMac17,1 slot exactly
  • Major-brand chips tested for reliability in A1419 EMC 2834 systems

Targeted iMac Upgrade

This 4GB DDR3L 1866MHz SODIMM module is built specifically for the Apple iMac Retina 5K 27-inch Late 2015 model. It matches the factory PC3-14900 specification and 204-pin form factor required by the iMac17,1 system identifier.

Low Voltage Operation

The memory runs at 1.35V, reducing power draw and heat output compared to standard DDR3 modules. Unbuffered non-ECC design with 1Rx8 ranking ensures quiet, stable operation during everyday multitasking and application loading.

Sustained Workload Stability

Major brand chips undergo rigorous testing to maintain performance under continuous memory pressure. The single-rank layout supports consistent throughput for long rendering or virtualisation sessions without throttling or errors.

How it compares

Measured against everything we stock in Model-Specific Memory Upgrades, at today’s prices. Recalculated every night.

Price $19.99
Cheaper than about 91% of the 21,161 comparable items (median $397.99).
Total capacity 4 GB
Lower than about 90% of the 20,941 comparable items (median 32 GB).
Price per GB $5.00 per GB
Cheaper than about 77% of the 20,941 comparable items (median $8.19 per GB).

New to this? Buying memory and SSDs with crypto — what to check, what it costs to pay, and what is never asked for.

Specifications

Product
Brand nameA-Tech
Product lineA-Tech DDR3 Apple Mac RAM Memory Upgrades
Total capacity4 GB
Performance
Rated speedDDR3L 1866 (PC3L 14900)
Processor
ChipsetMajor Brand Chipset
Memory
ECC supportNo
Buffer typeUnbuffered
Memory rank1Rx8
Heat spreaderNo
Power
Rated voltage1.35 V
Compatibility
Compatible systemsApple Mac Systems

Questions about this item

How do I install this 204-pin SODIMM in my iMac 27 Late 2015, and what step do people often miss?

Power off, unplug, lay the iMac face-down on a soft cloth, remove the memory-access door, press the module firmly into the slot until the side clips click — many forget to seat both clips fully.

What maintenance or replacement will this DDR3L 1866MHz module need later?

No scheduled maintenance; if a future macOS update requires more than 4 GB, add another matching 1Rx8 1.35 V stick rather than replacing this one.

What limit appears first under sustained heavy workloads with this single-rank 4 GB stick?

Capacity — 4 GB fills quickly, forcing macOS to swap to the SSD, which slows responsiveness before any thermal or voltage limit is reached.

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