I have a different board and it has PCI-E and SLI as well. It has a power connector next to the graphics card slot for connecting a power connector if the graphics card doesn't have a power connector onboard. Having said that it says in my manual that this power connection is for when you use 2 PCI-E cards together. They way I read it if theres only 1 card you don't need a secondary connection as the PCI-E can supply more power than AGP could, so I think it'll work ok.
Notice I said I think it'll work ok this is because the manual on my board doesn't make it clear. Hopefully someone else can clarify.