I recently bought HD 7770 and found out mine psu don't have 6 pin needed to power gpu.
I saw threads here about molex bridge cable (2 x 4 pins to 6 pin) so I got one and my question is do I need to connect both 4 pins or just one? And will it harm gpu because it's bridged and not general 6 pin straight from psu?
Connect both of them to molex and the 6-pin to GPU. This is how it works. It wont harm anything.