can someone help me understand power requirements a bit better?
contrary to my previous post, i have decided to go with a single card solution since evga offers full warranties. currently i have a coolermaster 650w 80+ psu (amd64 x2 3000+ processor 125w, and the usual peripherals)
will my powersupply be able to handle a nvidia 560ti rated at needing a 500w psu (says nvidias page)? sounds like it doesnt give much headroom and will work my psu hard. how about 560ti in SLI (not that i have the power rails for it but just wondering)?
how are power supplies divided up? if i have a 125w processor, 500w graphics card, etc, do you just add up the wattage for 625w?
Or based on a little knowledge and some experience, I can do a SWAG (Scientific Wild Assed Guess) and come to within 10% (I'm usually a little high) of my Kill-A-Watt power meter.
In spite of the 500 watt recommended size, I estimate that your system at full load would pull about350 watts and no more than 400 watts.
One of my systems has an OC'd Q9550, 4 GB DDR2 RAM, a GTX260 - a card that needs about 4 or 5 amps less than a GTX560Ti, 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 can look at the Coolermaster website or your PSU to see the specific power output by rail. Your CPU has a maximum 125W draw. The Nvidia 560Ti uses 170W of power according to Nvidia. Most of the CPU and GPU power is supplied by the 12V rail(s) of the PSU. In your case you'd need a Minimum of 25 amps (and probably more like 35 amps to cover the other hardware that uses +12V), on the +12V rail. The Coolermaster GX-650 has plenty of +12V power with 52 amps. so if this is the PSU you have you'll be fine.
There are numerous online PSU calculators that will allow you to plug in your hardware and determine exactly what you need for a PSU, but it looks like your's is fine for the application.