As graphics cards will be supplied with more and more power, I had my GTX 760 first must be fired with an additional cable (Molex to PCI-E). The supplied adapter that often found with other graphics cards, but then took two Molex connectors, thus ensuring little more tangled cables in the housing. So I just ordered this adapter, and am satisfied. The price is extremely cheap, supply of yesterday to today (Dealer: lets-sell) and the product fulfills its purpose. More can not be said. It is a cable and working.
Would you like to soon decide to buy a new graphics card, you should always make sure in advance how these must be wired, if your power supply is providing these connections and whether you may need to be retrofitted with such an adapter. Meanwhile, 2 PCI-E power cable per graphics card any more and, depending on card 6- or 8-pin cable required rarity.