DDR3 vs DDR2

July 26, 2010 at 12:45 PM (Technical Articles)

How Ram Works?
DRAM ( Dynamic Random Access Memory ) , a transistor and a capacitor are paired to create a memory cell, which represents a single bit of data. A capacitor is like a small bucket that is able to store electrons. The problem with the capacitor is it has a leak, within milliseconds it become empty. there fore it is the responsibility of CPU or memory controller to refill it frequently, that is nothing but refreshing.



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Point 1: Refreshing factor: Then obviously it is an overhead, several milliseconds are wasted to refresh the RAM. DRAM works by sending the charge through the appropriate column ( CAS Column Address Strobe ) to activate the transistor at each bit of in the column. The length of the time to read or write and refreshing the RAM is very short , it is expressed in nanoseconds.

Point 2: A memory chip rating: 70ns means that it takes 70nanoseconds to completely read and refresh each cell. We can say this as refresh rate.

Point 3: CAS Latency: Column Address Strobe latency is nothing but , it is the time interval between the time memory controller tell to access a memory to Memory module and the time data is available on the out put pin. In simple words, CAS Latency is difference between the time request for data and the time the data is ready at the output pin.

These are the brief description about the RAM ( Dynamic RAM is taken for Reference ). Now will discuss the difference between DDR2 and DDR3 RAMs.

See the images of DDR , DDR2, DDR3 and make out the difference.

DDR2 vs DDR3

DDR2 vs DDR3

 

1> Higher Operational Frequency:
DDR3 will be running at 800MHz to 1666MHz, it would double the frequency of DDR2.

2> Low Voltage and Power:
Every Product that release in the market will release certain amount of heat , it is obvious right?, if it takes something inside, it should give something back :-) and hence the temperature of the glob is increasing day by day. So now all the developers will keep in mind about the power consumption. DDR3 operates at 1.5V instead of 1.8V for DDR2. So it saves 16% of the power. DDR3 is built with the feature like partial refresh. Precious system battery power will no longer need to spend on refreshing. ( see point 2 written above ). Partial refreshing is nothing but a technique which reduces the rate of refreshing and hence less power consumption.

3> More Internal Banks:
DDR3 consist of 8 internal bank but DDR2 has only 4. This reduces access latency by allowing advance pre-fetch.

4> As the speed of the DRAM memory system increases, so as the amount of Cache memory built onto the MPU. New processors come with 1MB to 2MB of on-board cache memories. That means there might be no main memory hit during normal non-graphical operations.

So these are the brief technical information regarding difference in DDR2 and DDR3 RAM, and if anybody is planning to upgrade or buy a new system, then go for DDR3 RAM and feel the difference, give up an enhanced speed to your system.

 

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1 Comment

  1. Arun (chopu) said,

    Brief and crisp info about DRAM buddy, Doing good, Continue doing, u will reach your goal one day…..

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