there is 23 amperes mentioned in the 12 v rails and there are no any such cables that connects the pcie..there are 2 extra power connectors for hard disk,can it figure out the pcie power connector?well,im using this psu since 4 years without a problem so i have not upgraded it.do i need to upgrade it too?
Depends upon how strong your power supply is. Most psus with only a single PCI-E connector don't provide enough amps on the +12V rails to support a high end card. Most are 450W or lower models anyway, so another plug wouldn't help. Most 550W and higher psus have 2 or more power connectors.
If you have a really good power supply with a single PCI-E connector, then a molex converter should work. Note that most adapters convert two free molexes to a single PCI-E plug.