Choose low-density over high-density memory
Upgrading your computer’s memory is a cost effective way of improving performance. If you search eBay, you’ll see sticks of memory for sale at unbelievable prices – but the money you save comes at a cost that these sellers fail to advertise.
These memory sticks are more often than not cheaper high-density memory. Sometimes this type of memory won’t even work with your machine, and when it does it can actually be slower than what you already have! The density refers to how the memory is stored inside the chips, if you look at a stick you can tell if it is high density if it has ’128Mx4′ written on the chips. Low density will appear as ’64Mx8′.
When buying more memory for your computer, make sure you buy low-density memory. If in doubt, use Crucial’s memory advisor tool to find the ideal chips for your machine.