Memory for Desktop Computers

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Last Updated: December 11, 2008

Today's Best Choice 2GB of SDRAM memory is all you need, but 4GB has a lower per gigabyte cost.  1GB is required to play new games at the highest quality setting while Photoshop users will notice a speed increase.  2GB is good for heavy multitasking with dual core or quad core processors (Intel Core 2 Duo, Core 2 Quad, Core 2 Extreme, Core i7, Pentium D, AMD Phenom X4, Phenom X3, or Athlon 64 X2) or editing High Definition (HD) videos.  Read more about memory amounts for different situations at Tom's Hardware.  SDRAM is for desktop computers only.  The wide range of prices has to do with supply and demand and not performance. DDR2-667/PC2-5300: Buy 4GB (2×2GB) for $53 including shipping. DDR2-800/PC2-6400: Buy 4GB (2×2GB) for $45 including shipping. DDR2-1066/PC2-8500: Buy 4GB (2×2GB) for $60 including shipping. DDR2-533/PC2-4200: Buy 1GB for $14 including shipping. DDR2-667/PC2-5300: Buy 1GB for $12 including shipping. DDR2-800/PC2-6400: Buy 1GB for $18 including shipping. DDR2-1066/PC2-8500: Buy 1GB for $20 including shipping.

Dual Channel DDR2 SDRAM

If you want the fastest memory available, then buy "dual channel DDR2 SDRAM."  The "dual channel" means they are sold in pairs and are specifically designed to work together.  They run about 5% faster than non-dual channel memory.  In reality, you won't notice the difference.  When the memory is sold in pairs (e.g. 2×2GB), then you are most likely getting dual channel RAM.

Buy the Right Kind of Memory

Check the motherboard owner's manual to make sure you are buying the right kind of memory.  The motherboard is the largest circuit board inside the computer and will determine if you need DDR, DDR2 or DDR3 RAM.  Also check to see what speed the processor and motherboard can handle.  Faster memory is more expensive and if the processor or motherboard can't take advantage of it, then faster memory is a waste of money.  Faster memory in a slower computer will still work though.

Most motherboards come with 4 memory slots and work with 1, 2 or 4 memory modules (pictured above).  Memory modules are commonly referred to as memory sticks.  A computer will theoretically run the fastest with two memory sticks as compared to only one or four sticks.  You won't be able tell the difference.  However, two 2GB sticks (2×2GB = 4GB) may be less expensive than a single 4GB stick.  Some motherboards want each memory stick to be the same capacity and may not work if you mix and match a 2GB stick with a 1GB stick, for example.  The motherboard owner's manual should mention this.

Quad core and dual core processors should have 2GB of RAM.  This will allow several memory hogging applications to run at the same time at full speed.  Gamers and video editors need 2GB of RAM to run their software.  1GB of RAM for everything else is fine.  Memory is too cheap to have less than 1GB for Windows Vista and Windows XP based computers.  Windows 95/98/ME won't benefit from more than 512MB of RAM.

Numbers and Faster Memory

Here are some numbers associated with memory.

• The larger the number, the faster the speed for numbers after "DDR" or "PC."  For example, DDR2-1066/PC2-8500 is faster than DDR2-800/PC2-6400.
• The smaller the number, the faster the speed for memory timings.  For example, 2-3-3-5 is faster than 3-4-4-8.  These numbers are only important if you want to overclock the computer.  Otherwise, ignore them.  See below for more detail.
• The number of pins on a memory module do not affect speed.

Memory Timings and Overclocking

Some memory boasts it has lower latencies (wait times) such as CAS 2 instead of the slower CAS 3.  CAS is the first number in a string of timing numbers that may look like 2-3-3-5.  ExtremeTech (Aug 2008), Tom's Hardware, The Tech Report, Trusted Reviews, ExtremeTech (Aug 2006) and Bit-Tech state the 1%-5% speed difference is not noticeable and not worth the 30%-100% higher price when comparing CAS 3 to CAS 2.  However, if you are technically inclined and want to change the voltage on your computer to make it run faster, then spend the extra money on the CAS 2 memory.  This is called overclocking and you will notice a speed difference, per Firing Squad.  See PCStats.com for a good article on overclocking for beginners.

Buying Your Own

There is a dizzying array of memory types, so it's best to read the computer manual first to see what kind you need.  Not all combinations are possible.

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