androbourne :
No you shouldn't need more then that just to get into the BIOS.
However, if you can give us a parts list. We can give you some recommendations.
For starters. I never recommend less then a 750wt PSU. While a 450wt may work. It wont be at optimal wattage ranges for that level of PSU. Plus it limits your upgrade options.
Yes we need full parts list because we have no idea what parts you have to know if you have potential incompatibilities.
Now the suggestion of a 750w PSU with no knowledge of system specs is completely misguided.
Even overclock systems with a GTX 1060 run efficiently on a quality 650w PSU, key word being quality.
Too much wattage can actually be a bad thing in the way of inefficiency. When you start getting down to 10-15% draw on the PSU your efficiency level drops and so you could actually use more power to make 100w on say an 850w PSU then on a 550w PSU.
Typically, the poeple buying 750w PSUs for a 300w systems are buying cheapo 750w psus, the kind that cant even safely output 450w and when (not if, but when) they die they take out your GPU and motherbaord with it.