ddr dimm is not compatible with the ddr 2 because of the notches. the different notch positions will keep you form installing it.
The Slot layout.
the different notch positions keep someone from installing a DDR DIMM or DDR2 DIMM in the wrong memory slot.
The two communicate in different ways, so they are incompatible software-wise. They are also physically incompatible due to a different pin arrangement, different notch locations, and different voltages.
The DDR DIMM is an older type of RAM. DDR DIMM is not compatible with other kinds of RAM which is why a person that has an older PC has to choose a DDR DIMM memory as a replacement for one that broke.
There is a notch that prevents installation, even though the modules are the same size and have the same number of pins. Notch position between DDR and DDR2 are diferent. Also, the memory socket on a motherboard is diferent for all types of memories. If the memory socket is design for DDR you can't put any other memory type but DDR and so for all other types.
DDR 3 240 pin DDR3 DIMMs · Are currently the fastest memory commercially available and can support triple channeling, dual channeling and can be installed as a single DIMM.
One.
# 4 DDR II DIMM memory slots (supports up to 4GB memory) # Supports 1.8V DDR II DIMM # Supports dual channel DDR II 667/533 DIMM # DDR2 PC5300/PC4200 # 512MB or 1GB Modules # Install like memory in each channel for Dual Channel operation # If only 2 DIMMS installed, place in same channel (slot color) for Dual Channel, if installed in adjacent slots, memory will run in single mode.
1 offset
184-pin DIMM
168 pins are used on SDRAM DIMM. 184 pins are used on DDR DIMM. There are either 30 pins or 72 pins used on SIMM. 184 pins are used on RIMM.
DDR