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PC Memory (RAM) Computer memory type information, help buy the correct type for your Laptop or System.

PC Hardware aims to provide a website dedicated to providing useful information about computer hardware, news and guides to get more from your computers.

 

Why not speed up your computer by adding more memory, make sure you buy the correct memory.

Increasing your Computers Memory by buying and adding more memory, also known as RAM (Random Access Memory) for you computer can be the cheapest and easiest way to give your PC a significant speed improvement.

PC Memory provides a place for the system to store information before writing or reading it from the hard drive and memory is also allocated to allow programs to run.

Which Computer memory do you need?

Unsure what type of memory you need?
Use the Memory Advisor Tool Below or click through and install the scanner which will run a test on your system.

Crucial Memory Advisor Tool -
Use system scanner if unsure which memory you need

If your system is under 10 years you will use either DDR, DDR2, or DDR3. The newer the system (2008 onwards) it almost certain to be DDR3, for slightly older systems DDR2 is most likely. If still unsure use the links below to check or search your motherboards specification to check if DDR3, DDR2 or older systems.

Installing Computer Memory Guide
Laptop/Notebook/Netbook Memory
What is the difference between one speed of RAM and another

Jump to DDR3 DDR2 DDR Sections

Online Store Links for Memory:

Buy Computer Memory UK Customers
Crucial UK Memory Finder Tool [Go]
Crucial UK Apple Mac Memory [Go]
DDR3 Prices DDR2 Prices
dabs |

Buy Computer Memory US Customers Crucial USA Link
Crucial US Memory Finder Tool [Go]

Windows 8 does run better than earlier versions and the ability with newer tech to have fast boot times, near instant sleep and wake functions and with more apps and other things running 4GB+ should be looked at. Especially as memory prices have come right down now so if you have decent hardware, are running 64-bit then load up with memory to get the most from it.

We would suggest 2GB+ as a minimum ideally 4GB or higher for Windows 7-8 where 64-bit and faster processors benefit greatly from ample memory to get you moving and with fast boot and sleep times. Around 512MB to be the minimum for running a typical system running Windows XP and general applications. As a general rule the more memory you can have available the better your system will perform. (Although on 9x systems large amounts of memory can cause your system to slow down without adjustments being made).

For Vista/Windows 7 or Windows 8 users at least 1-2GB for light users, ideally 2-4GB or more for heavy users and especially users of video and graphics 4-8GB+. As these operating systems come with additional services and larger footprints the more you can afford the better.

Vista/Windows 7 can be sluggish even on dual cpu systems running 1Gb. If this is doubled or tripled the performance increase is dramatically improved. Windows 7 has been changed to be run better than Vista and depending on the version of 7 512MB-1GB would run at a usable rate.

How much memory your Windows OS will recognize depends on which version of Windows you are running. 32-bit versions of Windows will see (and utilize) only 3GB or 3.5GB. To utilize more memory you will need to install a 64-bit version of your OS.

Below is guidance about the different memory types avilable, to ensure compatability please check your motherboard manual or related website for advice.

DDR3 Memory (240-pins) is the latest memory standard (2008 onwards) taking over from the previous DDR and DDR2 standards. Although DDR3 comes with 240-pins the same as DDR2 the notch is in a different place so you can not install the wrong type.

DDR3 is not backward compatible with DDR2 in addition to the notch the voltage runs at a lower 1.5V than DDR2 1.8V. DDR3 memory will not fit into a standard DDR2 DIMM socket or an earlier DDR memory socket.
To use DDR3 memory, your system motherboard must have 240-pin DIMM slots and a DDR3-enabled chipset. You can buy faster DDR3 memory they will work but if you use a mixture of speeds they will only run at the slowest speed.

Official DDR3 standards:

pc3-6400 = 800mhz
pc3-8500 = 1066mhz
pc3-10600 = 1333mhz
pc3-12800 = 1600mhz

 

Guide to type of memory you are likely to have or need:

DDR3 DIMM Core i7 / i5 / i3 Phenom - Dual-Channel Kits
DDR3 DIMM Core i7 - Triple-Channel Kits, AMD X2/X3
DDR2 DIMM
Core 2 / Pentium Dual Core / AMD X2 ...
DDR1 DIMM Intel Pentium 4 / AMD Athlon XP / ...

DDR Memory (184-pin DIMMS). These were introduced in 2002 to replace the earlier SDRAM format. To use this type of memory you need a 184-pin socket for the module to fit into.

DDR 184 DIMM Memory

DDR Memory is available in different speeds of PC2100, PC2700, PC3200 (DDR400), and PC4000 (DDR500). The modules can be used singly or how desired however you cannot mix different speeds together.

DDR2 Memory (240-pin DIMMS). This format builds on the technology of DDR. This standard has more pins and its main developments are the ability to run faster whilst consuming less power.

DDR2 Memory

To use DDR2 memory you need a 240-pin socket for the module to slot on your motherboard. DDR2 Memory is available in many different speeds including PC2-3200 (DDR2400), PC2-4200 (DDR2533), and PC2-5300 (DDR-667).
The modules can be used singly or you can install different speeds of DDR2 memory together if your motherboard supports the faster speed however faster modules will perform at the lower speed.

This may be worth considering if you want to run Dual-Channel memory where you must use the same speed and ideally matching pairs to ensure compatibility.

 

Crucial Ballistix DDR3 DIMM

What is the significance of the RAM speed?

When buying RAM, one of the most obvious questions is, whats the difference between one speed of RAM and another?

The clock frequency, or the MHz, of the RAM will determine how much data can be transmitted per second. The formula to work this out is:

Memory clock frequency x 2 (for double data rate) x 64 (bits transferred per second) / 8 (to give the result in MB).

So 800MHz DDR2 RAM will be able to transmit:
400 (remember the clock frequency is half that of the effective speed) x 2 x 64 / 8 = 6400MB of data per second.

The eagle eyed amongst you may have noticed the 6400MB figure looks familiar. A standard practice is to advertise RAM by the amount of data it can transmit. This is denoted by PCxxxx.

So for example 800MHz DDR2 RAM is also known as PC6400. A simple calculation to convert the PC figure to MHz is divide the PC figure by 8. However for some RAM speeds such as PC8500 (1066MHz) it isn't quite accurate because the actual figure for 1066MHz RAM should be PC8528, but this doesn't look very nice so the manufacturers round it up/down.

 

RDRAM, and older SDRAM, EDO on next page

Looking for Memory for your Notebook or Laptop?

Laptop Memory Section
What is Dual-Channel Memory?
What is the significance of the RAM speed?
Installing Computer Memory Guide

Buy Computer Memory UK Customers
Crucial UK Memory Finder Tool [Go]
Crucial UK Apple Mac Memory [Go]
DDR3 Prices DDR2 Prices
dabs |

Buy Computer Memory US Customers Crucial USA Link
Crucial US Memory Finder Tool [Go]

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