I don't think that's quite what he meant. I think he means: What makes it different than a non-SLi PSU. And the answer is nothing, other than the fact that a SLi-ready PSU will have 2 6-pin PCI-e power connectors. Having enough amps on the 12V rail doesn't always mean it's SLi ready. But you can use a adapter to change 2 molex connectors to 1 6-pin PCI-e connector if your PSU has enough amps to run 2 cards in SLi. Simple really.....