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- Understanding RAM:
Recently in the world of PC's, there
have been a lot of changes and advancements in the way your
computer communicates with it's various components. As
a result, there has been a massive increase in the types of
RAM available.
To better understand the various types
of RAM, let's take a brief look at what influences the
type of RAM a PC uses.
- Clock
Speed: Until recently, the
dominant type of RAM was known as SDRAM which was rated by
it's 'clock' speed in MHz.
The clock speed of your RAM generally
matched or exceeded that of the Front Side Bus of your
Processor. So, if you had a Front Side Buss of 133 Mhz,
your RAM would generally also have to be 133 MHz SDRAM, or
PC133 RAM as it was designated.
There are a number of RAM types for
SDRAM that are still in wide use, which we will chronicle
shortly.
-
Front Side Bus:
The Front Side Bus, or FSB, of your
computer is essentially half the equation to your raw CPU
speed.
The Front Side Bus is multiplies by a
CPU Multiplier, or a factor that is determined by the
manufacturer of a CPU, to give you a RAW CPU speed.
For example, let's take a 900 MHz CPU
running at a 100 MHz Bus Speed..
CPU Speed= 900 MHz
Bus Speed = 100 MHz
Multiplier = 9
Or 900/100=9
For this reason, it is important to
have RAM of an adequate speed to handle the System Front
Side Bus, or your computer may suffer severe damage,
unstable operation or simply fail to boot at all.
-
RAM Classes:
As technology improved, Bus Speeds
and Consequently CPU speeds increased. As a result,
new types of RAM were developed, primarily RDRAM and
today's most popular DDR-RAM
Let's take a close look at the various
types of RAM:
 | SDRAM: The older, slower of the
various RAM Types available today, it is still widely in
use in many systems as it is slowly phased out in favor of
faster more efficient types of RAM. SDRAM may be
utilized in both earlier AMD and Intel based Systems. |
| DDR-RAM: Double Data Rate RAM
is the newest most widely used memory type and the leading
competitor to the proprietary RDRAM. DDR-RAM makes
use of technology that allows two-executions per clock
cycle, or 2 executions per megahertz, to effectively
double the speed of the RAM, lending to it's often
referred name of 'Double-Pumped' memory. For
example, 266 MHz DDR-RAM makes use of 2 instructions per
cycle of 133mhz RAM, or 133mhz x 2 = 266 MHz RAM.
DDR-RAM is currently used in both AMD and Intel Based
systems. |
| RDRAM (RAMBUS): A proprietary
RAM type that was heavily promoted by Intel and designed
specifically for the ultra fast FSB of the new Pentium 4
processors, RDRAM is expensive, has bulky heat sinks
attached to the Memory cards and currently offers no
appreciable benefits over DDR RAM. As mentioned,
RD-RAM is restricted to Intel based systems. |
Understanding RAM Speed:
Previously with SDRAM, the speed corresponded to it's PC
rating, such as PC133 SDRAM related directly to 133 MHz RAM.
With the advent of DDR-RAM and RDRAM,
the PC rating effectively went out the window and has become
very confusing to consumers that may not be 100% clear on
how the new ratings work.
Below is a Matrix for Cross Referencing
RAM speed to PC Rating:
RAM Speed Matrix:
|
PC Rating |
Type |
Memory Speed |
| PC66 |
SDRAM |
66 MHz |
| PC100 |
SDRAM |
100 MHz |
| PC133 |
SDRAM |
133 MHz |
| PC1600 |
DDR-RAM |
200 MHz
(100x2) |
| PC2100 |
DDR-RAM |
266 MHz
(133x2) |
| PC2700 |
DDR-RAM |
333 MHz
(166x2) |
| PC3200 |
DDR-RAM |
400 MHz
(200x2) |
| PC3500 |
DDR-RAM |
533 MHz
(266x2) |
| PC800 |
RDRAM (RAMBUS) |
800 MHz
(200x4) |
| PC1066 |
RDRAM (RAMBUS) |
1066 MHz
(266x4) |
Which RAM is right for you:
By now you should have a pretty good idea of
the various types of RAM and their differences.
Determining the type of RAM that is right for you is
dependant on 3 things:
| Motherboard: What Front Side
Bus settings, and there fore RAM, your motherboard
supports. |
| CPU: The type of CPU will help
determine what the FSB of your System will be and what RAM
should be mated to it, ideally opting for the highest
supported RAM of your motherboard. |
| Affordability: Depending on
Price, you want to generally pt for the highest speed RAM
your system will support without breaking the bank.
You will of course need RAM with at LEAST as high a bus
speed as your CPU and Motherboard to get the most out of
your CPU, but if your budget allows it, it wont hurt to go
a little higher. |
Final Note on Speed: After
all this, we sort of turn the tables here and have to say
-Raw speed isn't everything.
There are other factors that attribute
to RAM and system performance, such as band width and
through-put, but the information above should give you a
fairly rudimentary understanding to get what is best for
your system
And of course, when in doubt, ASK! 
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know by clicking here! |
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