Foxconn A7DA-S 3.0 AM3 AMD 790GX HDMI ATX AMD Motherboard
This board will support two GPUs, or four if you use risers. This is one of the least expensive boards with the number of PCI Express slots available. It also has onboard AMD Radeon HD 3300 graphics which means that running your display need not reduce your MH/sec from your mining cards.
I bought this board a couple of months ago and it died after a couple of hours. This board is the RMA replacement which I just received. It is new in box and has not been opened. If it dies on you I will be happy to assist with a second RMA or warranty replacement if necessary.
Accepting reasonable BTC offers. This board is located in the US. If you are elsewhere in the world, the shipping charges for a 5 pound package are quite high; I'm willing to ship it if you're willing to pay the extra shipping charges.