I find it amazing that the 5970 can get a 25% oc just on the air cooler. My friend has one with a 1090 core clock.

Well the only thing that's going to compare to 2x5970's is 3x480. And with higher resolutions ati wins out. In this comparison I'd say good going nvidia for having a 100>90>70% scale rate for up to tri sli on the 480. If Ati would tweak their drivers they could do the same I bet.

I'd personally go for the 480x3 because of the better scaling. You're spending 1500 usd either way. 16x16x8 speeds on the mobo is okay, the "x8" is a 2% performance decrease from "x16," no biggy.

The OP's mobo has 3 x PCIe 2.0 x16 (at x16/x16/x1 or x16/x8/x8 mode)...That good with 3x GTX 480?

Also, will the Tri SLI setup run cooler than the 2x HD5970? And power consumption?

Simply, No and No, but I thought I seen he had no budget so maybe its not an issue. I"m using a 1200watt psu right now but not even using half. He'd need a 1200 watt or better to run 3 of those, and buy aftermarket coolers too.

OK, I think i've narrowed it down to two options:

1) Sapphire HD 5970 4GB toxic

OR

2) two GTX 480 (Fermi) in SLI

What do you think I should go with?

Most will probably pick the two GTX 480, but I have had better luck with the Sapphire units than any other.

Not to mention, I really don't feel like fooling around with a water-cooling unit for the two GTX 480s.

unless you will use the cards for several years then liquid cooling isn't a practical option anyways; GPU blocks for the GTX series can be expensive.