High Density vs. Low Density Memory - SDRAM
All of the 512MB SDRAM & 256MB "High Density" modules we sell are built using 'High-Density DRAM' technology. Your system's motherboard must accept 512MB in each memory slot in order for these modules to work properly. In the event that your motherboard does not accept 'High-Density' SDRAM, you system will either show the memory module as a smaller size (i.e. 256MB or 128MB) or will not read it at all. The best way to know is to consult your system/motherboard documentation or the manufacturer's website.
We sell 256MB SDRAM in 'High Density' & 'Low Density' configurations. The 'High Density' modules are built using the same technology as the 512MB modules mentioned above... Thus having the same system requirements. Your system's motherboard must accept 512MB in each memory slot in order for 'High Density' modules to work properly. As with the 512MB modules, if your system/motherboard does not support 'High Density' SDRAM these modules will only be read as a smaller size. The 'Low Density' modules are built using low density DRAM technology, this type of module is generally compatible with a wider range of systems. In any case, you are advised to check your motherboard/system documentation for support information.
High Density vs. Low Density Memory - DDR/DDR2