I wish to build a system with (3) 5970's that I already have along with an AMD 890FXA or 990FXA chipset motherboard that supports at least (3) PCIe slots @ x16, x16, x8 (e.g. ASUS Crosshair IV Formula, MSI 890FXA-GD70). I have +plenty+ of cooling through a special case I made and the room in which I'd like to install it has two sets of air conditioning units.
1) Radeons: I'm certain I have (1) Crossfire cable to connect a pair of 5970's, but what do I need to connect three?
2) Power: What are the power requirements? Rather than buy a super-expensive Silverstone 1500w PSU, can I use (2) 750W PSUs (1 PSU for two 5970s and 1 PSU for 1 5970 and the rest of the system)? For example, could I power up the PSU for the two 5970s, then power up the rest of the system? This would save about $200.
3) Chipset: What advantage is the 990FXA chipset (e.g. GIGABYTE GA-990FXA-UD7) over the 890FXA for such a machine? If I could use the 890FXA, this would save $80 or so.
4) Drivers: Any tips on drivers I should use for a Win7 or MS Home Server 2008 OS?
You are going to have to take it up with the guy on that video. With normal CCC drivers, you cannot run 3 in crossfire. The maximum number cores you can run with crossfire is 4, which 2 5970's have. To go beyond that requires special hacked drivers I imagine.