Question about SeaSonic x series

[ac53]

Hi, I'm currently working on my first build but I was wondering if the SeaSonic will fit in in a case that mounts the PSU on the botttom, since the fan is on the bottom. The case I bought is the NZXT M59. I'm also wondering if the 650W will have enough overhead for future expansion. The current system I have is:

AMD Phenom II X4 955 Black Edition Deneb 3.2GHz
ASUS CuCore Series EAH5770 CuCore/2DI/1GD5 Radeon HD 5770 1GB
GIGABYTE GA-790XTA-UD4 AM3 AMD 790X
ASUS DRW-24B1ST/BLK/B/AS Black SATA 24X DVD Burner
G.SKILL Ripjaws Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333
Samsung SpinPoint F3 1TB HDD
Three case fans.

I want to know if I will have enough for an SSD, a 2nd HDD, and maybe Crossfire/SLI in the future. Thanks for the help.

[mdk777]

1. case vents bellow PSU. OK if not on carpet
2. can always invert PSU, fan facing up.(what I would do)
3. plenty of power, could run 5870 in crossfire.

[Smoothie]

I think you can do crossfire fine, not sure about Sli as the new Nvidia cards draw more power (about 200W per card). I think its a safe purchase if you only use one GPU and do some overclocking. If you do some major overclocking (CPU+GPU) and will run 3 way sli or crossfire then I would look into a 850W or higher PSU. Seasonic will be releasing 850/1000/1200 units soon.