That's not really how power supplies work. Any power supply will do what is demanded of it. There is a point at which, if your hardware requires too much energy (note that the rate at which energy transfers is power), a protection circuit of the PSU will kick in. For example:
OPP - overpower protection analyzes the power from the wall, and if it exceeds a certain value, the PSU shuts off.
OCP - overcurrent protection monitors the outputs of the power supply, and if the total current on a cluster of wires exceeds a certain amount, the PSU shuts down.
Point be told, the wattage label on a power supply - in this case 430W - is as meaningless a value as it gets. It reeally does not mean anything
at all. If you are interested to read into more detail on this, you can check out
this article. So, since a computer PSU in a realistic scenario won't ever hit its theoretical maximum power, there is no such way "not having enough power" could ever be the cause of any problem with a PC.
Unstable voltage is what can cause problems, but a power supply should not affect FPS. In your scenario, I'd think FPS would be related to your graphics drivers. What was your previous GPU? What are the rest of your specs? It could be that you didn't fully clean wipe your previous graphic drivers. Or maybe you didn't even install the new ones?
Note: The rare scenario where a PSU may affect performance if it is has high voltage fluctuation which can heat up and throttle the motherboard power supply.