Im using CM Real Power 450W ALCX and it work flawlessly. Until recently it struggle to supply enough power fo my overclocked CPU and new X1800GTO. The cheapest solution is use cap tikus PSU 350W just to power my X1800GTO but still it isnt enough for my X1800GTO.

The reason why your overclock drop is because of lousy PSU, you called that a good PSU? If you realiy want a reliable overclock buy something more expensive and better like Enermax, OCZ, PC Power & Cooling and Antec. Those are high quality and reliable PSU maker. I'll buy Enermax FMA 535W PSU if my budget allows. If LYP sold PC Power & Cooling PSU I'll buy one even though it super expensive. Remember that cheap thing no good and good thing not cheap

I believe in your system a CM Real Power 450W is enough, but if you can afford the 550W SLI is even better.

Yep, but I rather spending more to get a better quality PSU then settle for less expensive model so I dont have to bother to buying another one. I dont understand some people settle for something cheap say that it performs similarly, but the truth is it isnt. The price diffrence reflects its capabilities and reliability. Im a student and I dont mind saving to buy new PSU, my pocket money is RM70-RM170 a week and I save RM50-RM100 a week. RM20-RM70 to eat and everything else, no PTPTN whatsoever