I seriously doubt it would do any good except in a few rare cases where gpu and cpu power consumption are fairly low.
BTW, since you ve considered upgrading your entire system, could you tell us your new budget ?
I am on tight budget but I will try my best to get upto Rs 25000. I think Hard Disk, CD Drive, CPU Case can be used, so I need a new motherboard, processor, RAM, PSU & a medium type graphic card.