2x5970+GTS250? or 5970+5870+GTS250?

Hello all,

Ok so I have been mulling this for a while and could use some fresh insights on the matter.

Using a MSI 890FXA-GD70 AM3 AMD 890FX SATA 6Gb/s USB 3.0 ATX AMD Motherboard.

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

I was wondering if I could push two 5970's and a GTS250 for physx as the board has 4 pcie 2 x 16 slots.

assuming a 425W power draw under full load per 5970 for a total of 850W + 235W for the GTS 250 and the 1090T CPU at 125W

I am looking at power draw of 1210 give or take. I have a 1500W PSU in mind to accommodate all this plus room for OC.

That being said, power isn't so much my concern as I will work and rework component requirements and adjust as needed that is simple math.

My concern is this:

I know there is a ceiling beyond which one would just be throwing money away as far as graphics performance goes. As I understand it 2x5970 is that ceiling. I happen to have a GTS250 lying around and started wondering if I could throw it into the mix. I know about the Nvidia block on Phyx while using ATI but I have a work around just wondering if anyone has tried this and what those results may be.

I also realize that Physx titles are few and that there is Havoc for ATI but hey since I already have it I figured why not try it?

Other thoughts:

Could a 5970 and 5870 in Xfire plus the GTS250 be a better way to go?

I have also read that the 5970's are under clocked and run like 2 5850's so could it be better to run 3 x 5870's in Xfire plus GTS250 to get full performance out of ATI cards? I realize 2x 5970 is like 4 cards plus the GTS250 for a total of 5 should be better than 4 cards total but hey no harm in making sure...

In case you are wondering I will be water cooling the entire system with a split loop (Video cards on one line, CPU etc. other line) dissipating 2000W of heat.

P.S. Please keep it serious, comments on how much I make you make or don't make are not the topic here this is about the Tech let's keep it that way. Thank You.