"The X7DB8/X7DBE supports up to 16 GB (32 GB) fully buffered (FBD) ECC DDR2 533/667 in 8 DIMMs. Populating DIMM modules with pairs of memory modules of the same size and same type will result in Interleaved Memory which will increase memory performance."
Q - are the sticks ALL the same Mfg, Speed 533 MHz and 667MHz, Freq, Fully Buffered ECC, etc...? If not then note the 16GB above
Q - How many and what Xeon are installed?