Here are a few recommendations...
MSI 890GXM-G65 AM3 AMD 890GX SATA 6Gb/s USB 3.0 HDMI Micro ATX AMD Motherboard
GIGABYTE GA-890XA-UD3 AM3 AMD 790X SATA 6Gb/s USB 3.0 ATX AMD Motherboard
ASUS M4A79XTD EVO AM3 AMD 790X ATX AMD Motherboard
I would try and go with a motherboard that has Crossfire at x8,x8 minimum versus x16,x4... IMO