I have a Precision T7500 (2 E5540 processors) with 6GB of memory and upgraded the memory with 4Gb more.

After I installed the new memory, the computer would power-up but not boot.  I took the new memory out, leaving only the memory that was in before the upgrade, and it still has the same problem.

I did a CMOS reset, but it didn't help.

I took all the memory out and started with 2GB only (1GB on MOBO and 1 on riser). Same problem.

I changed the 2 sticks with 2 of the others but it didn't help.

I tried with 4GB and the problem remained.

I'm following the manual's instructions on where the modules have to go.

The diagnostic lights are: lights 3 and 4 are on (memory failure); but the workstation is only two months old, so I don't see how all the modules would be bad.

The original memory is Elpida PC3-8500 (1066Mhz) DDR3 DIMM ECC (unbuffered).  The description on the module is 1GB 1RX8 PC3-8500E-7-10-DP.

The new memory I got is the same as above but made by Centon (the code on the module is totally different).

Thanks for any help.