5-2-2-1 Memory beep code on Precision 530

I recently had to replace the Motherboard on my Precision 530 because of a Post problem and the new Motherboard is the same part number but im getting the 5-2-2-1 Beep code with my original memory.  The memory was working fine before the post problem.  I had some memory from another system that i used to troubleshoot the original post problem to rule the memory out that will work in my system now.  The bios version is A10.  The original memory is 4 sticks of 256mb 800fsb, the memory that works is 4 sticks of 128mb 600fsb.  Any suggestions would be appreciated.