450w is more than plenty, as you'll be around 175w at full system load. Even if your system is running a cheaper OEM power supply, I wouldn't worry about changing it (I just wouldn't overclock or anything)
Depends on the brand and model of your power supply, but a 450 watt PSU is plenty to run those two parts. Unless you have cheaply made and unstable model you don't need to change it.
450w is more than plenty, as you'll be around 175w at full system load. Even if your system is running a cheaper OEM power supply, I wouldn't worry about changing it (I just wouldn't overclock or anything)