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Green circuit board with black memory chips and gold edge connector

Computer Memory Solutions

Computer Memory Solutions 4GB DDR3 1333MHz SO-DIMM for Apple iMac 21.5-inch 2.5GHz Core i5

SKU CH-A585-X8FXY

4GB DDR3 1333MHz SO-DIMM module for 21.5-inch iMac 2.5GHz Core i5 systems

  • Total capacity4 GB
  • Rated speedDDR3 1333 (PC3 10600)
  • ChipsetMajor Brand Chipset
  • CAS latencyCL7
  • Memory timings7-7-7
  • Rated voltage1.5 V
  • 4GB capacity adds responsive multitasking headroom for everyday workloads
  • 1333 MHz DDR3 speed matches the iMac 21.5-inch 2.5 GHz specification
  • CL7 low latency tightens data access for snappier application response
  • 204-pin SO-DIMM form factor fits the factory memory slots directly
  • Tested compatible with iMac models including MC309LL/A and MC812LL/A

System-Specific DDR3 SO-DIMM

This 4 GB DDR3 1333 MHz SO-DIMM is built for Apple iMac 21.5-inch models with a 2.5 GHz Core i5 processor. It uses a 204-pin unbuffered non-ECC layout and runs at 1.5 V with CL7 timing. The module is validated for the MC309LL/A system identifier.

Steady-State Memory Behaviour

Major-brand chips and a 2Rx8 organisation keep data rates stable during extended workloads such as video rendering or large dataset processing. The CL7 7-7-7 timing profile maintains low latency without relying on aggressive voltage scaling, so throughput stays consistent when the system is under continuous pressure.

Mechanical Fit and Daily Use

A bare green PCB without a heat spreader slides cleanly into the iMac’s SO-DIMM slots, avoiding clearance issues with the factory cooling shroud. The single-stick packaging lets owners populate one of four sockets now and add matching modules later up to the 32 GB physical limit noted for compatible 21.5-inch and 27-inch models.

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).

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Specifications

Product
Brand nameComputer Memory Solutions
Model nameCM5126410600SODRH
Total capacity4 GB
Product type204-Pin DDR3 SO-DIMM
Performance
Rated speedDDR3 1333 (PC3 10600)
Processor
ChipsetMajor Brand Chipset
Memory
CAS latencyCL7
Memory timings7-7-7
ECC supportNo
Buffer typeUnbuffered
Memory rank2Rx8
Heat spreaderNo
Power
Rated voltage1.5 V
Compatibility
Compatible systemsApple Imac 21.5 in 2.5 GHz Intel Core I5
In the box
Included items1 Memory RAM Stick

Questions about this item

How much power does the 1.5 V DDR3 SO-DIMM draw when the iMac runs all day?

Standard DDR3 SO-DIMMs at 1.5 V typically consume a few watts under load; the module itself has no heat spreader and adds minimal heat to the iMac's internal airflow.

Does the 204-pin DDR3 1333 MHz module need any other parts to work in my iMac 21.5-inch 2.5 GHz Core i5?

No extra parts are required; the SO-DIMM installs directly into one of the four memory slots inside the iMac.

Can I keep the original Apple memory and add this 4 GB stick to reach 16 GB or the 32 GB maximum?

Yes, the iMac has four slots and supports up to 32 GB; you can mix this 4 GB module with existing sticks as long as the total does not exceed 32 GB.

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