DDR2 Vs. DDR3, which one is better?

Now, most of us know that DDR3 is the latest piece of technology we have in the memory segment. A logical person can claim DDR3 to be better without a doubt. But sometimes vendors delude us and force us to believe that DDR2 is better. So, why is DDR3 better than DDR2? If you don't know, this article is for you.

First you must know a little about JEDEC: To provide compatibility and interchangeability for computer memory, the structure and form factor are controlled by a standards organization known as JEDEC. JEDEC specifies voltages, speeds, timings, communication protocols, bank addressing, and many other factors in the design and development of memory DIMMs. Please keep in mind that JEDEC specs are official. They are a starting point for enthusiast memory companies. However, since there was never a JEDEC standard for memory faster than DDR-400 then DDR memory running at faster speeds is really overclocked DDR-400. Similarly DDR2 memory faster than DDR2-800 is actually overclocked DDR2-800 since there is currently no official JEDEC spec for DDR2-1066. Now, for those who don't know overcloking means running a device at greater speed than the official specifications it comes with.

So, what are the official JEDEC specifications of DDR2 and DDR3? Here they are:

Official JEDEC Specifications
	DDR2	DDR3
Rated Speed	400-800 MHz	800-1600 MHz
Vdd/Vddq	1.8V +/- 0.1V	1.5V +/- 0.075V
Internal Banks	4	8
Termination	Limited	All DQ signals
Topology	Conventional T	Fly-by
Driver Control	OCD Calibration	Self Calibration with ZQ
Thermal Sensor	No	Yes (Optional)

1. Rated Speed:

As you can see that DDR3 can reach much higher frequencies than DDR2. Thus, it brings improvement in speed. Now, you may say that you've seen DDR2-1066 so, what's special? The answer to that question is simple, like it is written above DDR2-1066 doesn't exist (officially since specifications to run it at 1066MHz, natively, aren't available) it is actually DDR2-800 factory overclocked to 1066MHz. Also, don't forget the fact that DDR3 can also be overclocked so, ultimately, it can be made to reach much higher frequencies.

2. Vdd/Vddq and Refreshing:

This defines the voltage at which the RAM runs. We see a 16% drop from DDR2 1.8 V to DDR3 1.5 V. Lower voltage means more power conservation and more room for overclocking. One more important thing is refreshing, we all know RAM needs to be refreshed again and again to avoid data loss. In case of DDR2 whole chip (DRAM) is refreshed even the portions not being utilized then. DDR3 introduces 'partial refresh' which means only the portions being utilized then will be refreshed and not the unused ones (applicable when the device is not in high performance mode). This comes in handy in mobile devices to reduce power wastage and extend battery life.

3. Internal Banks:

Internal banks are increased to 8 in DDR3 from 4 in DDR2. More internal banks allow advance prefetch to reduce access latency. It also helps to transfer more data at a particular frequency. In short, at a particular frequency DDR3 can transfer more data than DDR2. Although, overall DDR3 has more latency than DDR2 but clearly, pros outweigh the cons.

So, I have explained why DDR3 is better than DDR2. I did not explain rest of the specifications because they're beyond the scope of most of the users but, still, in short I'll say that all the remaining specifications of DDR3 are better than DDR2 like 'Fly-By' and 'Self Calibration'. DDR3, unlike DDR2, can also have thermal sensors (only if you want them) to help you monitor the memory temperatures especially in case you decide to overclock it.

I hope those who've read this article would now, know which technology is better. Also, remember DDR3-1066 performs better than DDR2-1066. Don't think since frequencies are same there will be no difference in performance. My personal advice is that before you go to buy something do your own research and don't trust vendors. Vendors want to sell what they have and they're there to fool you (especially in India). Most of them lack knowledge about the latest trends in technology.

REMEMBER: TRUST YOUR OWN KNOWLEDGE AND NOT OF VENDORS.

(If you like my articles don't forget to subscribe via E-mail or RSS feeds.)