Molex to PCI-e Adapter, 2 rails or 1?

[Abix Technology]

Hi Guys, been fixing and building pc's for 20 years and feel daft asking this one.... I'm building up a machine for a friend's son and needed to keep the budget down so we pimped an older machine with a GT740 and more ram. The card arrived today and has a 6pin PCI-e socket. I'd normally tell the client to upgrade the PSU but the 600w psu in the case looks good (and we want to keep the price down).
So, there is a 2 x molex to 6pin pci-e adapter in the box. If I use it, do I use 2 Molex on the same rail or use 2 seperate rails?
I don't know why but I've got it in my head the adapater will be shorting the rails out and cause problems in the long run!

 

[CountMike]

In 99% of PSUs Molex connectors are on same rail but on different wires. In case of that card it's really not important, it doesn't draw enough power to overload standard wires.