PCPartPicker part list: http://pcpartpicker.com/p/VPyjGX
Price breakdown by merchant: http://pcpartpicker.com/p/VPyjGX/by_merchant/
Video Card: MSI Radeon R9 280 3GB TWIN FROZR Video Card ($199.99 @ Newegg)
Total: $199.99
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2015-01-09 14:29 EST-0500
It's right at the edge of your budget but, it's the best you can get for your price range.
I would also suggest the R9 280. Another good card, although a bit (I'm sure you could find a deal) the GTX 760. I think (but am NOT sure) the R9 280 uses AM3+.
Socket does not matter for graphics card. What matters is if said board has a PCI-E X16 slot. If so, then it will be compatible. What CPU do you have? It is probably not powerful enough to bother getting a 280, as it will bottleneck it.