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Choosing RAM

Theirs going to be a few sections Current RAM (Random Accessed Memory) types, RAM Latency, RAM Features, RAM Needs,

RAM Needs
Think about your ram needs do you want to do a lot of video editing, games playing or do you just browse the net. I am going to list some tasks that ram will help with

128mb
128mb is the minimum amount of ram that Microsoft says windows Xp will work well with. With this amount of ram you should be able to browse the net and listen to music at the same time. Its highly probable though that you wont be able to run lots of programs at the same time so having multiple Internet Explorer windows open might cause system slow down.

256mb
With 256 ram you should be able to surf the net, play music and have multiple Internet Explore Windows/other programs open at the same time. It will also allow you to play most video games (if you have the right graphics hardware). You should be able to use most sound editing software quite well at this amount of RAM as well.

512mb
You should be able to do all of the above and more, 512mb of ram is about the minimum for Video editing and 3D modelling (High end Computer Aided Design).

1024mb
as above but more, as a example I have 1024mb of ram, have word open, am burning a cd , using Nero, MSNing with friends, a few Internet explorer windows and also watching 51st state on my TV from my pc

RAM Types
In generally on a modern system you will only have one choice of RAM and that will be DDR, although on a older machine SDRAM will be the RAM of choice and on some newer machines DDR2 s becoming a option.

SDRAM synchronous dynamic RAM
Speeds still available 100mhz/133mhz

People with older pc may be forced to buy SDRAM this is because you chip and mother board will not support DDR or DDR2. Anyone with a older system updating there ram or getting more needs to try there best to buy 133mhz over 100mhz the price should be negligible nowadays but the performance difference will be a lot..

DDR SDRAM Double Data Rate
Speeds available 200mhz/266mhz/333mhz/400mhz

The modern standard were RAM is concerned. I need to do a little bit of explaining though, the listed speeds are a visual cheat. A 200mhz chip of DDR ram actually runs at 100mhz the reason it is listed at 200mhz is because DDR ram transfers data at the beginning and end of its signal to the CPU effectively twice, were as SDRAM only sends data once. So the 100mhz is times by 2 to become 200mhz, 133mhz becomes 266mhz, 166mhz becomes 333mhz, 200mhz becomes 400mhz.

DDR ram in general is backwardly compatible, Meaning that 400mhz Ram could be used in conjunction with a CPU that only has a frequency of 200mhz.

DDR2
Speeds available 400mhz+

Only available on new motherboards, DDR has come to the end of its life it cannot feasibly attain higher speeds without redesigning its current architecture. That’s were DDR2 comes in with slightly different architecture that allows higher speeds that DDR. Its major downfall is its higher latency timings (see speed Latency) compared to DDR. Currently both DDR and DDR2 perform at a almost equal level making buying DDR2 the choice of someone who wants the best of the best. DDR2 will shine though when higher speeds come out that are not attainable with the DDR.

Frequency/speed
When buying ram you will see two things listed most commonly its speed the higher the MHZ the faster the ram can transfer date which brings us to the next commonly listed figure on ram its data transfer rate which is the speed at which the ram can transfer data here is a example

Generic Speed Transfer Rate
200Mhz PC1600
266Mhz PC2100
333Mhz PC2700
400Mhz PC3100

RAM Latency
When looking at ram you might see a set of figures listed under the latency heading that might looking something like 3-4-4-8, 2.5-6-6-8. There are many different combinations; the thing for a non in the know person to remember is that the lower the first number the better.

It is worth noting though that the difference to the average user is virtually none, what the first number means is the amount of cycles the ram takes before receiving new instructions, mean it can access parts pf the ram faster. Not 100% exact but it is about as good as I can type without getting too high tech.

RAM Features

Buffered and Un-Buffered Ram
Basically with un-buffered memory the memory controller on the motherboard addresses each memory chip on all RAM modules in the system directly causing system lag. Buffered memory uses a register that holds data back from the system meaning the system doesn’t get over run by data. To average joe this is a technology that doesn’t really help him. Its worth noting that that AMD 64 bit chips (754/939) have to use un-buffered memory.

Dual Channel Capable RAM
Although motherboard dependent I will explain it here. Dual channel memory allows the CPU to receive data from two different sources at one time. Like a car with two fuel lines or Twin Carbs.

ECC Error Checking and Correction
basically every RAM chip over 256mb (or a total of 256) stands a high chance of having errors which can result is system resets. Bearing in mind that a high chance is once in 700 hours (less with more ram), what ECC does is correct the error that’s why servers in general will use RAM with a ECC chip on it. The average Joe is not going to use (including me), ECC technology. Its a waste of money on a non-server machine that you could just spend on getting faster ram or better quality RAM.