PSU Calculators

I have used the Antec PSU Calc at http://www.antec.outervision.com/index.jsp
and so far so good but I was thinking of going to a crossfire set up of
2 Sapphire Toxic HD4870 1Gb
http://www.newegg.com/Product/Product.aspx?Item=N82E16814102815
I have one right now and just thinking of adding another.

Now when I use the Antec Calc it says for my set up i need 472W (thats with crossfire)
I know what the manufacture recommended PSU is but I would like some thoughts on this since the manufacture recommended is alot higher than the Antec Calc.
Is this one of those thing when a manufacture goes way high just to be sure they cover EVERY ONE thats going to use it With every set up in mind.:major

System specs:
Vista Home Prem 64bit
Sapphire Toxic HD-4870 1 Gb 800/1000
ASUS M4A78T-E AM3 motherboard
Corsair HX520W PSU
OCZ DDR3 1333 Reaper 2GB*2 (4GB)
AMD x3 720 2.8Ghz
West dig 650GB 7200RPM 16Mb cash SATA 3 (blue)
West dig 1TB 7200RPM 8Mb cash SATA 3 (green)
Antec 900 case 3 x 120mm TriCool blue LED / 1 x 200mm TriCool blue LED
LG dvd burner Sata 3
Memorex dvd burner Light scribe (IDE)

 

Did you change the capacitor aging option?
472W for a crossfire and tri core setup is not enough, you would need at least 750W
Corsair is the way to go.