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How Can We Recognize DDR1 and DDR2 RAM?

March 24, 2009

in computer hardware,computer memory,Macintosh,Windows

by Tina Gasperson

Q: How can we recognize DDR1 and DDR2 RAM? — Alim

The two types of RAM modules are similar in their appearance, but don’t get them mixed up because they are most definitely not interchangeable. If you accidentally purchase the wrong kind of RAM, it won’t even fit into your computer – and you’ll be heading back to the store.

DDR RAM is the most frequently used RAM module in today’s computer systems. There have been many different types of RAM, but don’t get confused – just remember DDR RAM or DDR2 RAM and chances are you’ll be safe. If you have a laptop, then the smaller SODIMM DDR RAM or SODIMM DDR2 RAM is what you’re looking for. Let’s look at the visual differences between these.

DDR1 RAM, also known as simply DDR RAM, has 184 pins that fit into the slot intended for it inside your computer on your motherboard. DDR2 RAM has 240 pins, and a notch at the bottom that is in a different location than the notch on DDR RAM. If you try to install DDR in a motherboard that is built for DDR2, or vice versa, you won’t be able to coax it into place, and even if you could it wouldn’t work.

For those of you with laptops, a smaller RAM module with the same computing power is available. These smaller modules are called SODIMMs and are available in DDR and DDR2 format. Both DDR and DDR2 SODIMMs have 200 pins, but alas, they are still not interchangeable. The DDR SODIMM has an off-center notch at the bottom, and the DDR2 SODIMM has a notch that is right about in the center. These notches are meant to prevent mis-installation, but that hasn’t prevented many a determined newbie from forcing the RAM module into a slot that wasn’t meant for it. If you do this, you’ll break either the RAM module or the motherboard slot, or both. To prevent this kind of error, take your old RAM module with you to the store and match it up exactly to whatever you’re thinking of buying.

Tina Gasperson (, affectionately known as Computer Lady by her family, has been writing about IT, home computing, and the Internet for more than a decade.


avinash 05.13.09 at 6:56 am

good help on the net. such help is great for the novish who wants to learn. i have a suggestion that there must be pictorial suggestions.

hussainsony 08.22.10 at 1:34 am

very useful information brother . Thank u . it would be nice if u upload the pics too. And how to Know with the numbers or letters writte on the ram s itself . Please reply

mhd 09.05.10 at 10:54 am

128mb pc2700 ddr 8c ddr1 or 2?

tabish 09.12.10 at 2:43 am


Gilbert Addison Amandze 10.28.10 at 10:04 am

how can i know the differences between the DRAM and SRAM.

Gilbert Addison Amandze 10.28.10 at 10:28 am


Santosh 12.10.10 at 9:41 am

Please put a image for better explaination, Thank you….

santosh 12.24.10 at 1:44 am

First thanks for the help and I would like to suggest you that if you put some pics so it will be better for newbie to understand

shashikant 05.07.11 at 5:01 am

Can i DDR1 RAM fit into DDR2 Memory module ?

any converter is available in market for DDR2 memory module convert into DDR1 Socket ?

kindly suggest us & reply on mail id

sharath 06.24.11 at 12:58 pm


The explaination was quit good. It helped me in understanding about RAM.

shashikant 07.13.11 at 3:11 am

Hi Expert,

Can i utilize USB pan drive space for expanding RAM capacity ?

any supported application requirement for this.

I know you will provide us concurrent solution
waiting for reply………

Some Guy 07.25.11 at 12:23 pm

To be honest, I didn’t find this very helpful. A picture would’ve been worth a lot more than words.

Nanda 08.03.11 at 12:17 pm

Nice i understood better :-)thanks :-).:-)is there any converter for ddr1 to ddr2 slot

Adeel Ahmad 11.16.11 at 12:53 am

Very nice information now i can recognized DDR and DDR2 by just looking at them….thanks…..

Carmen's Rrants 12.23.11 at 2:59 pm

on my old pc’s RAM, it is written that, DDR-DIMM. isn’t it DDR1 RAM?

Ajay 01.05.12 at 12:24 am

Good tips its very helpful to recognition of RAM

sunil 09.20.12 at 4:28 am

om my RAM mentioned PC 2700s 25330 DDR 333 MHZ CL 2.5 RAM
Can i replalce the RAM with other DDR 1 that is not mentioned “S” after 2700 or any number but no s.

Ephraim C. 10.04.13 at 12:19 pm

thanks for the tips. pls, i have a pair of ram with the information 256MB PC333 (32Mx64) 2.5V SN. Its it ddr or ddr2 and i want to upgrade it, which type should i use. reply via e-mail address.

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rileywilson74 04.06.15 at 4:40 am

Hey nice tip about DDR1 & DDR2. These RAM are best for computers & laptops. Before purchasing just everyone should make sure the quality of RAM, or at purchase online store.

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