After swaping DDR SDRAM chips on the board, I keep getting a memory error and it atuomatically decreases the system RAM by half.  The following error occurs before the OS is loaded.

Memory read/write failure at 0FFF0000, read FF10FF00 expecting FF10FF10.  Memory address line failure at 0FFF0000, read FF10FF10 expecting 00000000.  Memory read/write failure at 08000008, read 00EF00FF expecting 0EF00EF.  Decreasing available memory.