defected

I have an P4-- 2.93 GHZ ,256 ram ,915GL motherboard with my pc. some body told me that my processor is a junk caz. all the processor (mainly P4-- 2.93 GHZ ) are defected and the speed of p4-- lower catagories are far better then mine .Is it true

Can any one tell how to check if the RAM is defected. Mine is working well and it shows all 512MB in any softwares which shows the RAM amount. But I sometimes (not so often) have no video when the pc starts off.My PSUs 3.3V is now giving only 2.9V.Is that causing the AGP not to work?All other...