how to retrieve memory type ( rdimm or udimm)?

The first idea is using WMI Win32_PhysicalMemory and test if TotalWidth (bit count including check bits) is greater than DataWidth (bit count excluding check bits).

    gwmi Win32_PhysicalMemory | select totalwidth, datawidth, banklabel |  % { if ( $_.totalwidth > $_.datawidth ) {    "$($_.banklabel) is ECC memory type" } else {    "$($_.banklabel) is non-ECC Memory Type" } }

I don't know if exist a best way, and this check if memory is ECC or not.

try this for checking buffered/registered or not memory type:

$a = Get-WMIObject -Class "Win32_PhysicalMemoryArray" Switch ($a.MemoryErrorCorrection) {                    0 {Write-Host "ECC Type....:  Reserved"}                    1 {Write-Host "ECC Type....:  Other"}                    2 {Write-Host "ECC Type....:  Unknown"}                    3 {Write-Host "ECC Type....:  None"}                    4 {Write-Host "ECC Type....:  Parity"}                    5 {Write-Host "ECC Type....:  Single-bit ECC"} #unbuffered                    6 {Write-Host "ECC Type....:  Multi-bit ECC"}  #registed                    7 {Write-Host "ECC Type....:  CRC"}                }

as I didn't find any simple solution, i think I will do it by scraping the dell support site (providing the server ServiceTag on this url) : http://support.euro.dell.com/support/DPP/Index.aspx?c=fr&cs=RC1077983&l=fr&s=pad&ServiceTag=XXXXXX