I ordered a second gtx 470 and I my power supply only has 2 6 pin connectors but the 470 comes with 2 molex - 6pin adapters. Is there any performance issues using my pci 6pins for my top card and molex for my second?
There are a few older single rail PSU's, Im thinking Corsair units here that have plenty of power but only 2 Pcie Cables.
If you have a highend top quality PSU with plenty of power and enough spare Molex connectors then there is no reason not to as long as you know what you are doing. It is really not recomended and a change of PSU is the correct way to go. however should you choose to try it make sure you use 1 PCIE on each card and 1 Molex converted cable on each card to spread the load evenly.
If your PSU can handle it then it's fine, I've run 465s in sli using 2 of the molex adpaters on a seasonic that only had 2 PCI-E connectors without issue, but make sure you have enough amps on the 12v rails to handle the 2 cards in the first place.
Easy, use the 8pin PCI-e connectors, they are the same as 6 pin ones just with 2 extra pins, they can fit in 6 pin ones aswell, so the manufacturer didnt actually lie, 2x 8pin + 2x 6pin = 4x 6 pin PCIe connectors