How many Watts does my PSU need to handle my computer?

Question

Here are my computer specs, with all of this how much watts would my power supply need?

Two OCZ Dual Channel Titanium 4GB PC6400 DDR2 800MHz ( 2 x 2GB )

Adesso Multimedia PS/2 Keyboard, Mouse and Speaker 3-in-1 Combo

Two HIS Radeon HD 4850 Video Card - 512MB

Diamond TV Wonder HD 600 HDTV Tuner

Seagate Barracuda 7200.10 320GB Hard Drive - 7200, 16MB, SATA-300

AMD Phenom X3 8650 Processor - 2.30MHz, 3.5MB, 1800MHz (3600 MT/s) FSB, Toliman, Triple-Core, Retail, Socket AM2+, Processor with Fan

MSI K9A2 Platinum Motherboard

Two Lite-On IHAS120-08 Internal Super AllWrite SATA DVD Writer - OEM, 20x DVD±R, 8x, DVD+RW, 6x DVD-RW, 12x DVD-RAM, 48x CD-R, 32x CD-RW

Answer 1

Supposed to be able to run 2 4850s in Crossfire with a 550watt PSU. Thats taking the whole system into consideration, not just the cards. I run a rig with 3 hard drives, TV Tuner,sound card,  floppy, 2 rom drives and a ton of LED fans, tubes and 2 4870s in CF with a PC Power and Cooling Turbo Power 860 watt PSU. Heres a list of ATI certified PSUs for running ATI cards in Crossfire:

http://game.amd.com/us-en/crossfirex_com...

Answer 2

Maybe about 600-700w

Answer 3

Duhhh i don't know but this place does.