Yeah why only two cards per MOBO, you can at least put 4
I can, but when I put everything in an equation, it costed me the same as getting motherboards with 2 cards. So I went for simpler solution

How can it cost the same?
2 extenders cost around 5$ and I doubt a second MB, CPU, RAM, HDD cost less.

poor NOOB, you don't need expensive MBs having 4-6 PCIe 16x slots, you can just use the 1x slots you have free on the MBs allready you have. You don't have to use a powerful PSU just bridge two of the once you bought.
And there are simple cheap MBs with 1 PCIe 16x and 6 PCIe 1x slots like
ASROCK H61DEL it is made for mining and u can put 6 cards on it.
That is what I do - 3 machines with 18 cards total -
http://www.youtube.com/watch?v=OCTDN05LKao Look bro, I own a computer shop and service since '98, so no need calling me a noob, trust me I know prices. And considering my RMA over years, I know the risk of using bad PSUs. At the time when I was buying these, I considered everything there is available, abd for me, this was the best solution. Maybe I am just lucky but I never had a thing stop on me for a year now, and I have a total of almost 100 graphics cards. There is also a thing, thats called "ease of sale" when all stops at one time, and I took that into a consideration. Also I didnt have to "invent" any type of a custom rig or cooling, I made it as simple as possible, inserted 2 cards per motherboard and thats all.
What I am saying, everyone has his own ways, someone likes to link small power supplys, someone likes to make a custom housing, etc... I went for what I think is the best for my money, and never ran into a single problem besides having to change cables for electricity to my house
