Well I got around to making a list, for ease I didn't really shop around at prices so everything was done up at the egg, I also went along with manufactures I would purchase from and avoided products I know little about or just ones I would avoid based on how cheaply built they looked. Lastly, I tried to keep the builds as similar as possible and made sure to use all single-slot cooling for all video cards so none of the other slots would be blocked. The only thing is I am unsure of how well nvidia's multi-monitor support is. Also if I am wrong on any of the information just tell me so I can update it. I might tally up a skulltrail rig for fun later.
Build 1: Intel and NVIDIA Based
Motherboard: EVGA 132-CK-NF78-A1
---Note: I could not find the information about the electrical pci-express bus width.
Video Cards: 3x BFG BFGE88512GTOCE
Processor: Intel Xeon X3350
---Note: It's equivalent to the Q9450
Memory: Mushkin PC2-8500 4GB (2x 2GB Kit)
Operating System: Windows Vista Ultimate 64bit with SP1
Total Price
Build 2: AMD and NVIDIA Based
Motherboard: Asus M3N-HT Deluxe
---Note: Dual Cards x16, x16|| Triple Cards x16, x8, x8 bus width.
Video Cards: 3x BFG BFGE88512GTOCE
Processor: AMD Phenom 9850
Memory: Mushkin PC2-8500 4GB (2x 2GB Kit)
Operating System: Windows Vista Ultimate 64bit with SP1
Total Price
Build 3: AMD and ATI Based
Motherboard: Asus M3A32-MVP Deluxe
---Note: Dual Cards x16, x16|| Triple Cards x16, x8, x8 bus width.|| Quad Cards: x8, x8, x8, x8. Also 3870X2 counts as 2 cards so if you were to use two of those you would be using quad crossfire.
Video Cards: 3x Sapphire HD3870 100225L
Processor: AMD Phenom 9850
Memory: Mushkin PC2-8500 4GB (2x 2GB Kit)
Operating System: Windows Vista Ultimate 64bit with SP1
Total Price
Build 4: Intel and ATI Based
Newegg doesn't really have anything that has in this area that supports 3 physical cards in crossfire and from what I can see you would be forced to use DDR3 which is super expensive at the moment.
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For fun you could use 8GB in a (2x 4GB) kit for $600.
http://www.newegg.com/Product/...x?Item=N82E16820231182