Memory Speed

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For various technologies, there are certain bus and device clock frequencies that are standardized. There is also a decided nomenlature for each of these speeds for each type.

SDRAM

SDR SDRAM DIMMs - These first synchronous registered DRAM DIMMs had the same bus frequency for data, address and control lines.

• PC66 = 66 MHz
• PC100 = 100 MHz
• PC133 = 133 MHz

DDR SDRAM (DDR1) SDRAM DIMMs

DIMMs based on Double Data Rate (DDR) DRAM have data but not the strobe at double the rate of the clock. This is achieved by clocking on both the rising and falling edge of the data strobes.

• PC1600 = 200 MHz
• PC2100 = 266 MHz
• PC2700 = 333 MHz
• PC3200 = 400 MHz

DDR2 SDRAM DIMMs

DIMMs based on Doube Data Rate 2 (DDR2) DRAM also have data and data strobe frequencies at double the rate of the clock. This is achieved by clocking on both the rising and falling edge of the data strobes. The power consumption and voltage of DDR2 is significantly lower than DDR1 at the same speed.

• PC2-3200 = 400 MHz
• PC2-4200 = 533 MHz
• PC2-5300 = 667 MHz
• PC2-6400 = 800 MHz
• PC2-8000 = 1000 MHz
• PC2-8500 = 1066 MHz
• PC2-9600 = 1200 MHz

DDR3 SDRAM DIMMs

DIMMs based on Double Data Rate 3 (DDR3) DRAM also have data and data strobe frequencies at double the rate of the clock. This is achieved by clocking on both the rising and falling edge of the data strobes. The power consumption and voltage of DDR3 is significantly lower than DDR2 at the same speed.

• PC3-6400 = 800 MHz
• PC3-8000 = 1000 MHz
• PC3-10600 = 1333 MHz
• PC3-12800 = 1600 MHz
• PC3-14900 = 1866⅔ MHz
• PC3-17000 = 2133⅓ MHz