|"... never had issues before now and most of the parts are brand new."|
If this is an upgrade, possibly a major upgrade, we need to know this. Please include system make and model (if mfg'd system) or a list of all components, and a list of all upgraded components. Then outline the method you used to upgrade (all at once, gradually (one piece at a time), or in 'spurts') and how long has it been at its current configuration.
Important are the makes and model numbers of components and settings used and on the power supply, include a list of all specs (or a link) that include not only wattage, but all of the individual amperages from the label.
At this time, there are too many possibilities to begin to list until we have more information.
You have to be a little bit crazy to keep you from going insane.