What Is Down Compatible With DDR400?

DDR400 RAM is down compatible with other speeds of first-generation DDR RAM. All versions of first-generation DDR RAM are designed to be cross-compatible. However, the DDR RAM can only perform as well as the slowest installed RAM.



The number following DDR is the memory's top supported transfer speed which relates to how quickly it can send and receive data.

DDR333

DDR400 RAM will work with DDR333 RAM. However, the computer will automatically downgrade the DDR400 RAM's transfer speed to match that of the DDR333.

DDR266

DDR400 RAM will also work with DDR266 RAM. Like with DDR333, the DDR400 RAM will downgrade its transfer speed to match the DDR266 RAM's. However, the speed reduction is far greater in this instance and adding memory may not improve system performance.

Dual-Channel

Pairs of DDR RAM sticks can run a performance-enhancing feature called dual-channel mode if they have many similar features. Using down compatible RAM with pairs of DDR in dual-channel mode will disable it.

SDRAM

DDR400 is not down compatible with SDRAM. SDRAM is the previously used generation of RAM before DDR. Some motherboards support both SDRAM and DDR RAM, but they cannot use both types of RAM simultaneously.

References

• Aussie PC Fix: About DDR RAM Compatibility
• Arch Memory: DDR Speeds
• PC Tech Guide: About Dual-Channel