Knowing how to buy an external hard drive is extremely important with so many choices available on the market. With so many different brands, sizes, interfaces and storage capacities available, it can be hard to decide on the right external hard drive for your needs.
The first thing you should think about when buying an external hard drive is how you will be connecting it to your computer. External hard drives come in a variety of interfaces including USB, FireWire and eSATA. It’s important to know what kind of interfaces your computer supports before purchasing an external hard drive. USB is by far the most compatible interface available, and will work with 99% of computers out there, PCs and Macs alike. FireWire is similar to USB yet isn’t supported by many computers, so it should be avoided unless you are sure your computer supports it. External hard drives using an eSATA interface will typically be faster than USB external hard drives, but will only be supported by newer computers.
You should also be aware that some external hard drives require a power supply. External hard drives that contain standard 3.5 inch hard drives found in desktop computers will always require an additional power supply to run. External hard drives that use the 2.5” laptop form factor will typically not require an external power supply to run when connected via USB.
The trade off is size of the device, storage size and price. You can find 3.5” external hard drives with much larger storage capacity for a much lower price, although 2.5” hard drives are much smaller and require no external power supply to lug around.
Whether you choose a 2.5” or 3.5” external hard drives depends a lot on how portable you need the drive to be and how much storage capacity you are looking for. If money is no object and you just need a nice drive that’s highly portable and compatible with many different computers, a 2.5” USB external hard drive is the best choice.