Hi guys, Got a Corsair Builder 430w PSU here. It only has 1x PCIe. Would I be ok using a 4pin molex -> PCIe power cable with this to power a GTX 460 that requires 2x PCIe 6 pin connectors? 430W is more than enough to power the system, I'm not concerned about that, just the fact that I'm using a 1xPCIe and 1x 4pin molex on a GPU.
I know someone who is using them to provide power to a GTX 580, although he is waiting for a replacement psu to arrive. His old PSU went bang so he is having to use a older one with only 1 PCI-E connector, but it seems to be working fine for him.
Works fine, will only be an issue if you are trying to pull too much power on the rail, which it definitely doesn't sound like you will to me.
I always felt better with the type that are a Y with 2x molex 4 pin to a 6pin pci-e, as you can at least attempt to get it connected to 2 different rails for more stability and less stress on single rail.
Not a bad plan if you only need one 6pin PCIe. With two 6 pin PCIe needed like the OP you may as well just use the single molex to PCIe and just put each one on a different rail.
It's also worth pointing out that the molex connector itself is rated at upto 10A (120w), with the cabling rated at around 14A (168w). I doubt you've got anything else plugged into the same stretch of molexes but I thought I'd point it out just in case.