Run "lscfg -vp" and check the 2nd half (platform specific) of the
output. There should be some output with these location codes:
U0.1-P1-Cx-My (x is any digit from 1 to 4 and represents the processor
card, y is any number from 1 to 8 and represents the memory dimm)
The size is also written.

You can also run "lscfg -vp|grep Size" to get the size of the modules
(there are someother sizes but you should be able to separate them).

Bye
Holger