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PC Memory (RAM) Computer memory types and differences, help buy the correct type for your Laptop or System

Speed up your computer by adding more memory (RAM), make sure you buy the correct memory, DDR4 is the latest 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.

If your system is under 10 years you will likely be using DDR4, or DDR3 memory. If it is older than yes you guessed it maybe DDR2 or earlier. DDR4 is from 2014, and DDR3 around 2008. If still unsure use the information below to check the pins and dimensions alongside your motherboard model number to check format supported.

Which Computer memory do you need?

Windows 10 and 8 does need more memory to run smoothly over earlier versions, this is partly due to the ability with newer tech to have faster boot times, near instant sleep and wake functions.
And with more apps and other things running 4GB+ should be looked at, as a minimum. Especially as memory prices have come right down. So if you have decent hardware, are running 64-bit then load up with memory to get the most from it.

Even Chrome with a small number of tabs can easily take 1.5GB+ doing certain tasks and can use a fair bit of overall memory. Gamers or editing the extra headroom once you are in double digits makes handling and processing items with ease, feels a bit super computer like.

If a Raspberry PI or your phone has a fair bit of RAM then don't you think your system should as well.

Unsure what type of memory you need?

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:

Vista/Windows 7/8 can be sluggish even on older dual cpu systems running 1-2GB. If this is doubled or tripled the performance increase is dramatically improved. Windows 8 and 10 especially has been changed to be run a million times better than Vista and 7 (RIP) so get off that, depending on the version you might still be using WHY! 512MB-1GB could run at a usable rate, but just switch or install a different OS.

How much memory your Windows OS will recognize depends on if you have an older version of Windows


32-bit versions of Windows will see (and use) only 3.5GB. To use more memory you will need a 64-bit OS version.

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


DDR4 Memory started appearing in late 2014, it takes over from DDR3 and offers 50% more bandwidth, lower voltage (1.2v), and 40% more energy efficient than DDR3. DDR4 memory has 288-pins, the pins are closer together and the module size is the same as DDR3 around 5.25".
To use DDR4 Memory you just need a brand spanking system or one which uses the newer chipset on the motherboard which have been around for a few years now, and of course it will say DDR4 memory, or looup your board model and check :)
- The lower power demands but still high performance gains mean it will power the desktops, servers, gaming with the latest generation of CPU and motherboards, and of course help improve battery life of laptops, tablets, ultrabooks and mobile devices.


DDR4 Speeds:

PC4-21300 (2666Mhz) - PC4-22400 (28000Mhz) PC4-19200 (2400Mhz) - PC4-24000 (3000MHz) - PC4-17000 (2133 MHZ) - PC4-25600 (3200MHz) - PC4-26400 (3300MHz)


DDR3 Memory (240-pins) is still widely used and was the memory standard during (2008-2014) 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
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