650TX enough for this system?

[Stern]

e8600 - going to overclock so I can squeeze performance out of graphics card
4 GB ram
4870X2
2 HDD
1 DVD
case with 6 big fans

I did that power supply calculator thing but they don't have the 4870x2 so I just marked it as two 4870 in crossfire and it quoted ~520W. So this should theoretically be ok, I just wanted to get opinions from here.

 

[HOOfan 1]

It should be enough depending on how high you are overclocking