please explain ram

Hey there. Thanks in advance for any help you can give me. OK so all I really want is a good explination about RAM. More specifically what the numbers mean. I know that the rating in MHz is tied to the bus speed on the motherboard (is that right or is it processor?). All I know is that if your motherboard supports a higher MHz than your RAM is rated at, you aren't getting the full potential out of the RAM you could be using. What I would like to know is:

What is the 4-digit number that is always in the specs. For example: PC6000?

How does the timing work? More specifially, how can I use knowledge of timing to get the right ram for my system.

What is the most important (besides MORE RAM) aspect to consiter? The MHz speed? The 4-digit number? The timing?

Any help you could give me would be VERY appreciated. I have been looking for answers, but I can't find any. Also it is worthy to note that this is not a question about a particular system, rather a question to furher my understanding about RAM and how it works. Thanks!!!

 

Hello Mike,

??????????????????????

Specific Questions are much easier to answer.

RAM

A Geek could write a book. In fact one probably has.

Most electronic stuff is mass produced and 'type tested' at the end of the production line. This means that it is sorted into quality bands. The higher the quality band the more the buyer pays for the product.

So it is with processors and RAM. Speed is the quality parameter here. The faster the device will reliably perform the higher the price it commands.

The speed is measured by the Mhz. However different parts of a system operate at different speeds.

All the speeds are derived from a basic 'system clock' which generates control pulses at a standard rate. Devices which need to operate at other speeds get their control pulses by dividing or multiplying this clock by a fixed number, usually called their multiplier.

So the RAM speed is given by clock speed x multiplier and is the maximum that RAM will reliably operate at. The PCXXXX is a statement of this value. The RAM will operate with other lower multipliers. The multipliers are taken care of automatically on modern motherboards. However you should match the BUS peed to that of the processor when buying. RAM also comes in many different physical configurations and chip types. You need to consider these as well when you get to specifics.

Common modern types are DDR and DDR-2. The latter is taking over at the higher speeds.

Below is a table of some common conversions. The DDR-2

Module...Clock Speed...Bus Speed...Transfer Rate...Type
....................Mhz..........Mhz.........MBps
PC3200..........200..........400..........3200...............DDR
PC2-3200.......200..........400..........3200...............DDR-2
PC4200..........266..........533..........4266...............DDR
PC2-4200.......266..........533..........4266...............DDR-2
PC2-5300.......333..........667..........5333...............DDR-2
PC2-6000.......375..........750..........6000...............DDR-2
PC2-6400.......400..........800..........6400...............DDR-2

Your other question concerns timing. Simply, this is about the time taken for the system to access a given RAM module. You can adjust a whole set of parameters in bios to squeeze the last bit of performance.

Timing parameters are also called latency, precharge and other stuff. They are given by a bunch of four to seven numbers. You need expert help to mess with these.


Hope this helps

Studio T