Thanks Josh. I have solved the issue. It's because the memory is unbuffered. I checked the memory we have, and it's model number is KTD-PE313E/8G not KTD-PE313/8G. 
Hi, We have a PE T710 which we are attempting to upgrade the memory in. We have bought 18 x 8G DIMMs of Kingston KTD-PE313/8G memory for this server. The server has 2 x Xeon 5620 CPUs, and are trying to use the memory optimized configuration below. Slot A1 - 8GB PC3-10600 1333MHZ ECC Slot A4 - 8GB PC3-10600 1333MHZ ECC Slot A7 - 8GB PC3-10600 1333MHZ ECCSlot A2 - 8GB PC3-10600 1333MHZ ECCSlot A5 - 8GB PC3-10600 1333MHZ ECC Slot A8 - 8GB PC3-10600 1333MHZ ECC Slot A3 - 8GB PC3-10600 1333MHZ ECCSlot A6 - 8GB PC3-10600 1333MHZ ECC Slot A9 - 8GB PC3-10600 1333MHZ ECC Slot B1 - 8GB PC3-10600 1333MHZ ECC Slot B4 - 8GB PC3-10600 1333MHZ ECC Slot B7 - 8GB PC3-10600 1333MHZ ECCSlot B2 - 8GB PC3-10600 1333MHZ ECCSlot B5 - 8GB PC3-10600 1333MHZ ECC Slot B8 - 8GB PC3-10600 1333MHZ ECC Slot B3 - 8GB PC3-10600 1333MHZ ECCSlot B6 - 8GB PC3-10600 1333MHZ ECC Slot B9 - 8GB PC3-10600 1333MHZ ECC When the server is powered on it doesn't post and just stays with a blank video display. If we remove a DIMM from the 3rd slot of each channel ie A7, A8, A9, B7, B8, B9 the server boots. Any of the memory configuration modes that use 3 DIMMs per channel cause the server not to boot/post. Any ideas?
Memory Configuration Issuses PowerEdge T710