How do I know what size of wattage power supply I need?

The best answer we can give to this question is to go ahead and take an intelligent "guesstimate"! There are no hard and fast rules about what size of power supply any given PC needs as a minimum. Our advice would be that if you are replacing an existing power supply, then consider a new one at least of the same wattage as the old one. In addition, if you wish to build in a "safety margin" to allow for reliable running and possible future upgrades, consider adding 100-200 watts to the rating of your existing unit.

If you are building a new PC, most customers now buy a power supply rated in the region of 500-800 watts depending primarily on the performance level of their graphics card(s) and number of drives to be installed. But in any event if you are unsure about which power supply would be best for your PC then please do contact us by phone or email and we will be happy to give you a specific recommendation based on your budget.