if you are in Lahore or Karachi or living near, take your cpu to shop (galaxy knows a lot about these kind of stuff) and ask them about it. they will insert the card and check if it works or not.
as poton12 said you can use 4 to 6 pin molex converter but most of the time that fails like. i have this instructions card which says its a bad connection and is not recommended.
i have got an idea, let me do a little research.
ok here the deal..............
this card is really good and it doesn't need 6-pin connector. available at galaxy at 8600 Rs.
check out some reviews. it almost at the same level as 9600GT at some bench marks.
this review is for 512MB but the card at galaxy is 1GB.
crysis on this card.