It will work but:
1. You case might not be big enough
2. There might be SATA/Heatsinks blocking it
3. Your PSU might not have the juice
4. If you are buying a 4850X2 the 5850 delivers the same performance without scaling issues, DX11 support, less power-consumption, for $299 http://www.newegg.com/Product/Product.aspx?Item=N82E168...