SLI ready power supplies

[chaos]

Do you have to have a SLI ready power supply or can you run sli without. Whats the difference???
This is what I have right now:COOLER MASTER Real Power RS-450-ACLY ATX12V 450W Power Supply (not running sli at the moment)
What about this one: http://www.newegg.com/Product/Product.asp?Item=N82E16817190007

[Oklahoma Wolf]

You can use any good PSU with enough 12v power to run SLI, though some units will need PCI-E adaptors. The OCZ Powerstream 520w for example was a favorite for SLI despite the lack of the second PCI-E connector due to its single 33A 12v rail. Now, they have added a second PCI-E connector to make it SLI ready. The Sparkle FSP550-60PLG was another such unit - the new SLI model is the FSP550PLG-SLI.

[Stewie]

I have the Enermax 535W SLi-Ready PSU, and it's great. You can't be Enermax's reliability (IMO), and it comes with two PCIe connectors (hence dubbing it 'SLi-Ready). It also has an adjustable knob on the back to turn down the fan speed if you so desire; although I can't say I've ever heard it even with the fan on full (the unit has 2 fans).