I said to him that I cant afford brand name PSU... than i got the reply something like:
frontiers 450W PSU got "200W of real power" (think he overstated this bigtime), and it's normal for PC to restart on overload if the supply is weak...
Ok... i know its normal for PC to restart on overload if the supply is weak, but ... is it weak?
The cheaper power supply brands overstate their ability to run at full load. Some will die in just a few days. You can find an antec or ocz with rebate in the $40-50 range, even corsair 400w is sometimes this price.
OP, repeat after me/us: Never, ever, ever, ever, EVER be a cheapskate on your PSU.
If you can't afford a branded, certified PSU then you MUST drop something else in your budget to afford it. The PSU is the most important part of any build on which everything else depends - it's all well and good loading up with great, powerful hardware but if the PSU cannot handle the draw (not just delivering sufficient power but also sustaining that load for long periods of time) then it WILL fail, and in many cases can take other components with it.
It will simply cost you much more money in the long run.