If you are looking to optimise the way your computer works, you should firstly consider your choice in hardware and whether anything better for your needs might be available. Even the best computers can be optimised further with careful choices in specific types of hardware, so if you are attempting to improve the quality of your machine’s output, then starting with hardware is the best idea.
Hardware itself ranges from the relatively simple monitor to more complex machines such as the motherboard and RAM. Problems with hardware often arise first with software, but a software issue is not always related to hardware. If you do have a software problem then it is better to try to sort that out first, as it may have nothing to do with hardware and you could be spending money unnecessarily.
Problems with hardware are often easily diagnosed, and will usually mean that the component is either modified or replaced, depending on the intensity of the problem. Replacing individual parts can be inexpensive if you know exactly what you are looking for, and is often far cheaper than just replacing the entire computer.
Some types of hardware are far more expensive to replace than others, however. An optical disk drive is relatively cheap to replace in comparison to a CPU, or central processing unit. Bear this in mind if you need to replace a more expensive part, and try to get the best quality you can afford.