Try booting the system with just the board, processor and one stick of good RAM and Video card on the board. make sure no other devices are connnected. Check if the 4 pin connector that gives additional supplies for display is connected. Also if the board has onboard display, use it instead of the other video card.
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I did all that and still got nothing, maybe i should tell you more about my specs maybe that could help.
750w ps
amd2+ 2.2ghz quad core processor
gforce 8800gtx 768mb video card
corsair ram 2g
250g hard drive
creative XFi fatality edition sound card
MSI k9a2 platinum MB