People, you don't need much stronger GPU supplies, the onboard one is good enough and with mods it can provide what's needed.

An off-board supply is not that easy to use properly, you need to pay attention to wire voltage drop, you need remote sense, you need a way to clean the voltage of the EMI picked up by the connection wires and the hardest thing, you need to take care somehow of the poor transient response a remote supply has - especially if it's a linear design.

The onboard supply doesn't have these problems and with upgraded RC components, raised switching frequency and decent cooling it can handle exactly what the tiny 8400GS chip needs.