Power supply for 2 x fosgate P200.2 Amps

[wizkid77]

I currently have 2 x P200.2 fosgate amps using in my house powered by a 350w computer power supply. However it seem not to have enough power to run both amps. I notice that while in use that voltage drop from 12v to 10.5v when heavy bass is played and at that point the bass sounds distorted. I am looking for a cost effective solution.

Configuration:
1 x P200.2 Fosgate -------------> 2 x 12" 4 ohm 500w subwoofers bridge
1 x P200.2 Fosgate -------------> 2 x 10" 8 ohm 80w mid bass
2 x 6" 8" ohm mid
2 x tweeters