Samsung 2GB (1x 2GB) DDR2-400 PC2-3200 1.8V DR x8 240-pin UDIMM RAM Module Classification_ram-ddr4-2400-lrdimm-64gb-2x-dr but the effective rate is

but the effective rate is 2666 megatransfers per second (MT/s) because there are 1333 million rising edges per second and 1333 million falling edges per second of a clock signal running at 1333 MHz

and don't be surprised if you can actually upgrade your Mac with double the amount of RAM that was originally specified by Apple

This 4GB (1x 4GB) DDR3 1333 MT/s Dual rank

This RAM kit runs at 533MHz per second

Samsung 2GB (1x 2GB) DDR2-400 PC2-3200 1.8V DR x8 240-pin UDIMM RAM Module Classification_ram-ddr4-2400-lrdimm-64gb-2x-dr but the effective rate isProduct Overview This 2GB (1x 2GB) DDR2 400 MT s Dual rank, x8 configuration RAM module from Samsung is for use in DDR2 compatible systems and operates at 400 MT s with an overall transfer rate of PC2 3200. This RAM module also operates at a standard voltage of 1. 8V and is designed to allow you to run more applications simultaneously, switch between them faster, and provide a smoother computing experience. Technical Specifications Part No.