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Well obviously there are $1,000~$1,300 Socket G34 AMD Opteron 617x Magny-Cours 12-core series CPUs; they're for Workstations and Servers.
And there are Server MOBO's like the SuperMicro H8QGi+-F that can support 4 X 12-Core CPUs or 48-Cores total
http://www.supermicro.com/Aplus/motherboard/Opteron6100/SR56x0/H8QGi_-F.cfm
And there are MOBO's like the H8DG6 then can support a Single GPU and 2 X 12-Core CPUs or 24-Cores total
http://www.supermicro.com/Aplus/motherboard/Opteron6100/SR56x0/H8DG6.cfm {3/1/2 PCI-E 2.0 x16/x8/x4 (in x8)}
However, I'm not aware of ANY that support CrossfireX {assuming 'crosshair' is meant to be CrossfireX}, you could use the GPUs like ASUS ARES/2DIS/4GD5 Radeon HD 5870 X2 or HD 6990 which are essentially CrossfireX internally with 2 GPU processors but on a single PCIe.
If this is for 'Gaming' it IS a horrible waste of money, games crap-out after 2~4 Cores so you'll have 20-cores just sitting there doing nothing...