If you want to upgrade the power supply, there are additional things to consider. When adding or upgrading system components, such as memory, optical drives, or video cards, make sure that the power supply you purchase has a wattage rating equal or higher than the total combined wattage of all internal components. Since finding the wattage needed for each component can be extremely difficult, you can use the following general method to find a power supply that will properly provide power to an upgraded system:
Find the power consumption rating of each new component that will be added to the computer.
Total the power consumption ratings from all the new components.
Add the power supply rating of the original power supply to the total. The formula for these three steps is:
Original max power supply rating + Power consumption rating of new components <= New power supply max rating
You can subtract the power consumption rating for devices that will be removed when upgrading. However, it is better to have a higher wattage number in the event future upgrades are needed.
Purchase and install a power supply that has the same or better wattage rating than the total.
For example, when installing a new video card that has a power consumption rating of 230W, and the original power supply was 250W, you can install a power supply that is 480W or greater.