your new models are PC4200 DDR2 as I understand this is only supported by certain Intel based motherboards. If you go here click here you can find out what specifications of memory your system supports.
"Installation of Memory Modules (DIMM) P4V88/P4V88+ motherboard provides four 184-pin DDR (Double Data Rate) DIMM slots, and supports Dual Channel Memory Technology. For dual channel configuration, you always need to install identical (the same brand, speed, size and chip-type) DDR DIMM pair in the slots of the same color. In other words, you have to install identical DDR DIMM pair in Dual Channel A (DDR1 and DDR3; Blue slots; see p.8 No.6) or identical DDR DIMM pair in Dual Channel B (DDR2 and DDR4; Black slots; see p.8 No.10), so that Dual Channel Memory"
aka you need to pair memory off aka put memory in dual channel arrangement. I can see no mention of DDR2 other than the second slot for DDR aka DDR2 in the manual. It is quite unclear if you ask me.