Power supply - amps - voltages

A good 550 will run any CPU and any video card with a single GPU.

A 5830 needs maybe 10 - 12 amps for itself.

One of my systems has an OC'd Q9550, 4 GB RAM, a GTX260 - a card with similar power requirements to yours, a Gigabyte EP45-UD3P motherboard, 3 hard drives and an optical, and a Soundblaster card all powered by a Corsair 750TX.

Running 3 instances of Prime95 to load the CPU and 3DMark06 to load the GPU, it pulls 375 watts from the wall as measured by my Kill-a-Watt meter. Figuring 80% efficiency, the system pulls 300 watts from the PSU.

You have plenty of power. In fact if you have enough PCIe power connectors, you can safely power 2 video cards.

You should not have any problems. You have more than enough power to run a system with two Radeon HD 5830 video cards in Crossfire mode.

The general rule of thumb is a high quality 500 to 550 watt power supply with sufficient current (amps) on the +12 volt rail(s) can easily power a system with any single video card made. A high quality 700 to 750 watt power supply with sufficient current (amps) on the +12 volt rail(s) can power a system with two video cards operating in dual mode. There are a few exceptions like the new ATI Radeon HD 5XXX series cards which use less power due to their energy efficiency.

A high quality 500 to 550 watt psu will have a +12 volt rail(s) rated at a total of 40 amps. A high quality 700 to 750 watt psu will have a +12 volt rail(s) rated at total of 60 amps.

Your 650 watt power supply has +12 volt rails rated at a total of 54 amps. No problem!

That's absolutely right you should not be having any problem in running the system with that power this power you supply would be more than sufficient to run the whole system efficiently. I would also advice you to get a UPS so that it would ensure that the computer is safe when there is a power break down but providing you with the sufficient time to get your work saved and turn the computer off safely.