How DDR400 Works
One concern with the development of ever faster computer processors is that the faster the CPU, the more memory bandwidth you need to feed it. By doubling the data rate, memory manufacturers were able to keep up with higher speed processors.
What Does the Name Mean?
PC3200 Samsung 512 MB DDR SDRAM refers to a specific brand and kind of memory, operating at a certain speed with a given amount of bandwidth. For most computer users, bandwidth and capacity are the two most important factors. You want enough RAM that you can easily switch between applications and you also want it to be fast enough that you don't have to wait for the processor to get the data it just requested.
- Speed: Overall memory speed can express in two different ways: total bandwidth or clock frequency. PC3200 offers 3200 MB per second of bandwidth and runs at a clock speed of 400 MHz. There is a third factor, latency, which refers to the time from when the system sends a request to the time the data hits the pin, but that is less important to most users.
- Type: While DDR and DDR2 are both types of DDR memory, they are sufficiently different that they cannot work in the same slots. Samsung PC2-6400 comes in a 240-pin DIMM, while PC3200 DIMMs use a 184-pin interface.
How Do You Choose What Kind of RAM to Install?
The first question is always going to be compatibility. While a desktop uses DIMM memory, a laptop requires the smaller SO-DIMM form factor. You can get the same capacity in both module formats, but they are not interchangeable as the connectors are completely different.
- DIMM: This package is 133.35 mm long and runs at 2.5 Volts. It supports both registered and unbuffered options and has 184 pins.
- SO-DIMM: This package also runs at 2.5 Volts, it's 67.6 mm long and runs at 2.5 Volts. It has 200 pins and does not support either ECC or registered DIMMs.
Running Computer Memory
One question you always need to answer is whether your computer has a dual-channel or single channel configuration. With dual channel RAM, you get twice the effective bandwidth because the system can read from two modules at once instead of just one. The catch is that you then need to install your RAM in matched pairs so that the controller can take full advantage of the added performance. This means that two 512 MB sticks are a better choice than a single 1 GB stick when you're using this kind of setup. Also, check the slots on the motherboard as you don't want to install both sticks on the same channel, and it's not always obvious which slot goes with which.