Dell Dimension V400 Service Manual page 21

Memory can be increased to a maximum of 384 MB by installing combinations
of 3.3-V, 32-, 64-, and 128-MB non-ECC DIMMs in the three DIMM sockets on
the system board. Only 100-MHz DIMMs are supported.
NOTE: The system is designed for peak performance with specific DIMMs that
are validated through rigorous testing. The system may not recognize other
SDRAM DIMMs and may fail power-on self-test (POST).
For more information about the memory configurations, see "Adding Mem-
ory" in Chapter 2 of the Reference and Troubleshooting Guide .
See Figure 1-11 and Table 1-2 for jumper settings and descriptions.
jumpered unjumpered
)LJXUH  6\VWHP %RDUG -XPSHU - '
configuration
jumper (J9D3)
System Overview 1-13