Page 126, if you haven't found it already: support.dell.com/.../hom.pdf Just move the jumper over to CLR, power on and boot to BIOS (if present); power off, return jumper, and boot again.  This will clear the list of BIOS hardware, forcing the BIOS to rebuild it ... if this list is corrupt, then it could have a hard time adjusting to the new DIMM's.
I have a 2950 that had 4 x 1 GB of RAM.  I bought 4 x 4 GB of new memory (Certified).  I have updated BIOS, chipset, ESM and PERC. I removed the old memory and put the new 4 GB modules in the server.  When I try to boot the computer, fans spin up loudly, but no display activity and no drive activity.  The LCD on the server bezel does not display any error message, just reads PowerEdge 2900.  I had the RAM replaced, but still the same problem.  I have confirmed that the memory is DDR2 PC2-5300 FB 2R 667Mhz memory @ 4GB per module. I am not sure what to try next.  Any suggestions? Thanks
Problem with 2950 RAM upgrade