I have a 600 watt generic psu and im planning to buy a gtx 770 but the gpu needs 6 pin and 8 pin, sadly psu doesnt have both. how do I solve this problem without buying a new psu
Save your money and get a new PSU, I highly doubt that PSU is putting out 600w. If it doesn't have any PCI-e plugs it is ether really bad or never meant to run a card like that.
Save a few dollars and get an EVGA 210-GQ-0650-V1 $80 with $20 mail in rebate or a Seasonic S12II 620 Bronze for $63.
I would not chance using adapters to power the card and risk killing a lot more in your system when the PSU lets go.