FSP Booster X3
If you're running a mid-range system and are looking to upgrade to an SLI or CrossFire setup, one of your primary concerns should be your PSU. Both dual-graphics systems require an enormous amount of power - around 120W per card through the supplementary PCI Express power connector - and this can be too much for some PSUs to stand.
Enter FSP, with a supplementary power supply that is designed to take the burden of powering your graphics subsystem from the main PSU. It provides 300W of power and plugs directly into the mains. It also has a molex hookup into your PSU to synchronise the power phasing.
The X3 Booster comes with a fairly simple explanatory poster showing you how to hook everything up, in case you couldn't guess.
The device is designed to sit in a 5.25" drive bay. It's got a big piece of plastic on the front that is for aesthetic styling, but you may find you wish to hack the front around to fit in with the colour and mod-schema of your case.
The rear of the X3 has the power in port from the mains, the molex input to synchronise with the main PSU and the output to the graphics cards.
We hooked the FSP booster up to a 275W power supply that we pulled out of an Aopen small form factor chassis. We hooked up a pair of 7900 GT cards an an FX-60. We had no problems running our SLI system in games - proving that the 300W booster really is doing its job!