4. RAM

When you choose RAM (Random Access Memory) there are two types to consider. DDR, and DDR2. Most people who don't know much about this sort of thing will automatically think that DDR2 is better. Well, in fact it isn't. With the newest DDR2 running at a crazy 1 GHz, yeah it is the fastest, but it is also extremely expensive. All of the new Intel based systems will use DDR2.

DDR

DDR stands for Double Data Rate. In other words, memory like PC3200, has a true frequency of 200 MHz. But it is doubled to 400 MHz do to DDR. The standard is PC3200. Which means it has a peak rate of 3200 MB/s and runs at 200 MHz. So if you decide on slower/cheaper memory to save money like PC2700, it will hit 2700 MB/s at 333 MHz, resulting in slower performance. Stuff like PC4000 is used for overclocking mainly. When you see Dual Channel, you must have two of the same types of RAM modules. This doubles the bandwidth of the memory, and results in a nice performance increase. Every new system you build should run Dual Channel.

The numbers "2.5-3-3-8" are the memory's timings. The lower the better. The lowest I've seen to date that you can buy is 1.5-2-2-5. But some boards can't even run at 1.5. So the best to get is 2-2-2-5. With Intel based systems, timings are not as important. Intel CPU’s feed off of bandwidth more, so if you don't mind losing points in benchmarks, save yourself a few dollars. AMD systems generally love the lower timings. There is more on memory timings here.

DDR2

DDR2, also seen as PC2 sometimes will be run on the Intel systems and the newer AMD system that have socket M2. It is just a newer version of DDR and uses a lot of the same features. This a 240-pin memory module, DDR is 184-pin so remember that they will not work in boards that are designed for the other! Where DDR2 has high clock rates, you'd think it would be faster, but because it has slower timings, it really balances it out with the performance of DDR. So when choosing a system, don't worry about not having DDR2. It does not have that much of an advantage yet. This also can be run in Dual Channel mode.

Good makes of RAM are:

• OCZ
• Corsair
• Crucial
• Mushkin
• Kingston

When buying memory, there will be certain types called "value select". This just means that it has low timings and uses a cheaper memory chips. As I said before, 2-2-2-5 is about the best in DDR, and 2.5-3-3-8 is usually value select. With DDR2, PC4200 is usually the value series, and has timings like 4-4-4. If you are building a budget system for emails and such, you won't need really fast memory, or a lot.

For gaming you should have at least 1 GB. Some games now need about 2 GB to run full out. Prime examples of this are Battlefield 2 and Quake 4. 2GB is slowly becomming the normal, and with the release of Windows Vista with a minium requirerment of 1GB, 2GB is not looking to be overkill.

Dual Channel kits are the best way to buy memory, because the modules are tested togeather and will run in dual channel.

A quick talk on memory for overclocking too... if you plan on doing any form of overclocking, try to stay away from generic memory. If you are building on a budget or a just a net surfing computer, you can use some generic memory to save some bucks. If you want high performance, even without overclocking get good memory.

There are two main types of chips which are highly favoured among overclockers. These are the famous Winbond UTT (UnTesTed) and the Samsung TCCD. Winbond's best memory was BH-5, but it is out of production. A lot of people still swear by this ram. Its known best for its low timings (Generally 2-2-2-5) at a mid-high FSB (220-250 MHz). The disadvantage of this is that it requires a lot of voltage, about 3.3V before the results really start to show. TCCD is high FSB with relatively low timings (Generally 2.5-3-3-7). It is known for hitting 300+ FSB with a voltage of around 2.8-2.9V.

Experienced overclockers usually use the Winbond BH-5 where it uses so much voltage. These overclockers will volt mod their board to get a high Vdimm. You can get a product called the OCZ DDR booster that will enable you to get a higher Vdimm (Be sure to check motherboard compatibility before considering this). BH-5 use to be the best overclocking RAM, but has since lost popularity when TCCD came into the picture. It is still widely used though.

TCCD is a lot better for general overclocking, and beginners. Beginners are better suited where it does not require much voltage, but also pretty extreme overclocking where it can hit a 300+ FSB. It will take most things you throw at it. It will usually support 2-2-2 timings at 220 FSB with 2.7-2.8V. This type of RAM does not respond to voltage like the BH-5.

When building a high performance system, don't skimp on memory. And if you overclock, get the very good stuff. It is crucial to the system.