
1. Introduction
The RAM memory (Random Access Memory) of a computer is used to stock data during their treatment. The operating system will load in memory the useful files and all the datas of the launched programs. Its necessary to have an adequate quantity of memory.
The RAM has two important caracteristics :
- Speed data access : The access to data in RAM is very fast, a lot more than access to hard disks. It’s essential to give access to data in a quick way.
- Volatility : The data doesn’t remain in memory after computer shutdown. So this is not a storage device only a temporary data storage device.
If a computer doesn’t have enough memory, the operating system will simulate virtual memory using the hard disks, but like said above, the access on the hard disk is a lot slower than memory and the performances of the system will decrease.
So this is essential to make the good choice when choosing memory chips.
2. Size
The first thing to define is the quantity of memory do you need. The minimum memory is 512 Mo, but the this will be just enough even in Windows XP and it’s absolutely not enough for Windows Vista. For Windows Seven, you can have 512 Mo, but it will not be confortable.
Thats why i will advise at least 1 Go of RAM, but better is 2 Go. After, you have also to see the used applications to estimate the needed memory size. If you need to do images/movies treatments or play recent games 2Go is necessary. If you use more than 3 Go of RAM, be sure that you operating system can support that. Only 64 bit operating system support more than 3 Go of RAM. Generally, the last motherboards use the Dual Channel technologies for memory chips. Namely we control the chips by pair to have better bandwith. With this technology, you must use 2 chips with the same caracterics (two same chips will be better). Some motherboards have Quad Channel technology support. This is the same as Dual Channel but for 4 chips.
The motherboards have normally 4 memory locations. I advise to use only 2 for the start. This will make the update easier. It’s not really useful to buy 4 chips of 512 Mo instead of 2 chips of 1 Go. The prices are almost the same.

