IBM/Lenovo x Series System Server Memory Upgrade Configurator - choose your Model:

x3100 (4348-xxx)
x3100 M3 4253
x3105 (4347-xxx)
x3200 (4362, 4363-xxx)
x3200 M2 (4367, 4368-xxx)
x3200 M3 (non-Xeon)
x3200 M3 7327, 7328-xxx
x3250 (4364, 4365, 4366-xxx)
x3250 M2 (4190, 4191, 4194-xxx)
x3250 M3 4251, 4252, 4261-xxx
x3350 (4192, 4193-xxx)
x3400 (7973, 7974, 7975, 7976-xxx)
x3400 M2 7836, 7837-xxx
x3400 M3
x3450 (7948-xxx)
x3455 (7984, 7986-xxx)
x3500 (7977-xxx)
x3500 M2 7839-xxx
x3500 M3
x3550 (7978-xxx)
x3550 M2 4198, 7946-xxx
x3550 M3
x3610 (7942-xxx)
x3620 M3 7376
x3630 M3 7377-xxx
x3650 (7979-xxx)
x3650 M2 4199, 7947-xx
x3650 M3
x3650 T (7980-xxx)
x3655 (7985-xxx)
x3690 X5
x3755 (8877-xxx)
x3800 (8865-xxx)
x3850 (8863-xxx)
x3850 M2 (7141-xxx)
x3850 M2 (7233-xxx)
x3850 X5
x3950 (7363, 7366-xxx)
x3950 (8872-xxx)
x3950 M2 (7141-xxx)
x3950 X5
x3950E (7364, 7367-xxx)
x3950E (8874-xxx)