I returned the CM 650W PSU, and bought an Inwin Commander II 750W PSU, which had some good reviews.
However, it turns out that the problem is not in the graphics card, but it's a motherboard issue. Card works on the 2nd PCIe 16x slot, but not on the primay PICe slot. Seems like a defect in motherboard.
My motherboard manual says
2 x PCI Express 2.0 x16 slots (blue @ 16x mode, black @ 4x mode).
Blue one is not working. I'm using the black one at the moment. Does this mean that there will be a performance difference? I don't plan on going SLI.