also last question-what psu should i buy?i already have intex 450w bought 2 months back will that suffice for these?
No that will be a flop Sire, biggest mistake having a spanking new build housed inside a cheap local 'dabba' as well as powered by a local PSU.
Better invest in the Seasonic S12II 520W ~3700/- OR Cooler Master Silent Pro M600 ~6000/-. It will be sufficient for your needs as well as will provide future upgrade cover.