by Mike Stanley

Created on: July 02, 2009

This is a common issue I have seen in computers. A lot of people assume that buying memory sticks that are larger in capacity will instantly make the computer faster. While installing higher capacity RAM in a computer can increase performance, the main benefit of larger capacity is in how much more can run at the same time. However, a big mistake I have seen has been when someone purchases a memory stick that runs at a slower speed then the ones already installed in the computer. This actually slows the computer down, even when the capacity has greatly increased.

Here is a breakdown of how computers work. Everything in a computer is connected through a bus. A bus is simply a path that data travels on, much like a highway is for cars. The more lanes you have, the more cars can get to the same place at the same time. This is the capacity, or number of lanes in the road. Increased the speed of the cars, and the cars get there faster. Same with the data, if you increase the speed of the bus then the data is moved faster. Problem is, with buses in computer land, everything is forced to run with the slowest device on the bus, no passing allowed. Thankfully there is more then one bus in computers, or the whole system would slow down, but unfortunately still, if you put a slower stick of RAM in a computer, then all the RAM in the computer will only run as fast as the slowest stick of RAM. So if you have 800Mhz RAM, and you install 500Mhz RAM, then all your RAM will run at 500Mhz, and therefore negating most if not all advantage of the extra capacity.

Also, most all newer computers run dual channel memory, and these sticks generally have to be paired by size to work in dual channel mode. They will still work as single channel if not paired, but dual channel offers a huge advantage in performance, so it is wise to take advantage of it if your budget allows. It is generally best to buy matching sticks for the best compatibility for speed, size, and timing in order to get the most out of your system and to ensure dual channel is enabled. However, if you are on a tighter budget, it is possible to use different brands together and get desirable results. It is generally considered that dual channel will only work if the sticks are paired in BANK0 and BANK1 together matching in size, and BANK2 and BANK3 together matching in size. Although I have found that some systems will run dual channel no matter what slots you put them in, it is still best to match these bank pairs with matching size RAM, to ensure they work properly.

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