We need to know your MOBO manufacturer and model to determine what slots you have available.
Sorry it took so long - the MOBO is PT880 Neo series MS-7008 (v1.X) ATX Mainboard
version 1.0 G52-M7008X1
Designed for Intel Pentium 4 Northwood Prescott (socket 478) processors
2.42GHz 1.5GB or ram