Quote Originally Posted by zalbard View Post
Not a good idea since you'll need more CPUs, motherboards and such... Taking a slot by itself has a certain cost associated with it.
Why should you need more cpus? you can easily put 4 cards on one board, doesn't even need to be a 16x slot.
The only thing you probably would need is cards with a power connector since all the cards combined would draw to much from the board alone or get pci-e raisers with power cords.

In the end it still would be cheaper then a solution with a 290X.

Then again even with this you hardly will make any money, but that hasn't stopped the mining craze till now.