RAM: DDR, DDR2, DDR3, DDR4, DDR5

Differences in PC RAM

1. DDR (Double Data Rate):

• Speed: 200-400 MHz
• Voltage: 2.5V
• Pins: 184
• Features: First generation of DDR memory, doubling the data rate of SDRAM by transferring data on both the rising and falling edges of the clock signal.

2. DDR2:

• Speed: 400-1066 MHz
• Voltage: 1.8V
• Pins: 240
• Features: Improved over DDR with higher speeds and lower power consumption. Uses a 4-bit prefetch buffer.

3. DDR3:

• Speed: 800-2133 MHz
• Voltage: 1.5V (standard) or 1.35V (low voltage)
• Pins: 240
• Features: Further improvements in speed and power efficiency. Uses an 8-bit prefetch buffer.

4. DDR4:

• Speed: 2133-4800 MHz
• Voltage: 1.2V
• Pins: 288
• Features: Higher speeds, lower power consumption, and increased capacity per module. Uses a 16-bit prefetch buffer.

5. DDR5:

• Speed: 4800-8400 MHz (and potentially higher)
• Voltage: 1.1V
• Pins: 288
• Features: Significant improvements in speed and efficiency. Supports higher capacity modules and includes features like on-die ECC (Error-Correcting Code) for improved reliability.

These versions of RAM are not interchangeable. For example, you cannot put a stick of DDR4 when the motherboard supports DDR3.