I think there are few shops you can buy 500W+ power supplies, like Barclays, EGS, Nunet etc.
Mama langadi check kare nae, poddak ewage hoyala balanna monawada thiyana brand kiyala.
Power supply gana poddak danaganna one nam mea article eka tikak balanna.
http://buddhikamh.blogspot.com/2009/09/choosing-power-supply-unit.html
Oka mama tika kaalekata kalin liwwa ekak, eke link keepayak thiyanawa shop walatai, power supply ekak hariyata thoranne kohomada kiyana ekatai.