Considering RAM When Purchasing a New Computer

Okay, so last time we looked at processors, and found that the "core" of the processor is more important than anything else. Now we're going to take a look at one of the more confusing subjects. RAM.

RAM stands for Random Access Memory, and is often called Main Memory, or Primary Storage. This is by-far one of the most important aspects of a computer, as any program that is loaded HAS to be loaded into RAM first, and if your computer is out of RAM (as is very likely with sub-par vendored computers) your computer has to do a context switch, which saves all the RAM from another program to your Hard Disk Drive (HDD) to make room for the new program. This is a very time-consuming task and you do NOT want this to happen often. So you want to make sure you have as much of the FASTEST ram that you can find for your motherboard.

Important things to remember about RAM:

SPEED: This is usually represented as a further qualification of Double Data Rate (DDR) Ram. DDR comes in 3 different flavors at different speeds. DDR3 is the newest and best, due to increased pipelining and internal speeds, but have slower clock rates due to the complexity. DDR3 is the new de-facto standard for Intel's Core i7 processor, and thus it will become wildly popular as well. It IS "better" than DDR2 ram architecturally-wise but it needs to catch up in the latency department. Anyway. DDR31066 is the more common, but it also exists in 1333 and 1600 flavors. The difference you may ask?

It is mostly cycle time and data transfer rates. 1066 runs at 133 mhz, and transfers 1066 million data per second. 1333, runs at 166 mhz, and transfers 1333 million per second, and 1600 runs at 200 mhz, and transfers 1600 million per second. As you can see, 1600 is clearly better, but not all motherboards support it yet.

Note: Sometimes a concurrent speed definition is given as PC-(number). This is a rounded version of the peak transfer rate, and is basically the same as the DDR3-1066 definition.

AMOUNT: This is really the only other thing you need to worry about. It is almost always given in the GigaByte(GB) range, and usually ranges from 1GB to 6GB per "package". The package is the number of channels the RAM is. Single channel (1 DIMM) is pretty much no longer in use anymore. Dual Channel (2 DIMMs) is being out-phased by Tri Channel (3 DIMMs) RAM. So when it says 6GB of ram, and is Tri Channel memory, you know it's 2GB per DIMM (or 'stick'). The highest I've seen available on non-server motherboards is 64GB, but that number is almost impossible to reach due to insufficient DIMM slots available.

These are the two important things to remember, but there ARE other considerations, such as: Latency (CAS Latency), Timings, Voltage, and Compatibilities. The voltage you really should never have to worry about, and should never change unless you know what you're doing. Compatibilities should be already resolved if you're buying through a whole-computer manufacturer (Dell, HP, Apple), but you should be aware that not all CPU's are compatible with all types of RAM, if you're building your own computer. Latency is another way of measuring speed, but is not as important as the Data Transfer Rates.

Anyway, this is my guide on buying memory (or considering memory when buying a computer). Stay tuned for part 3: Motherboards!