If you go into a computer store, eBay or browse a memory manufacturer’s Website, the choices for memory can get rather overwhelming. Many people consider only the amount of RAM they want: 512MB modules, for example, or perhaps 1GB or 2GB modules. FSB (front side bus) speed is a consideration. There’s DDR, DDR II, and DDR III and then there’s... and on it goes.
Recently, however, we've encountered more questions about high-density versus low-density RAM.
Generally speaking, low-density 1GB modules are made with 16 chips, 8 on each side, using 64MB x 8 device, while high-density 1GB modules are made with 16 chips, 8 chips on each side, using a 128MB x 4 device. We’ve checked, and not all RAM is actually labelled one way or the other. You might have to look on the chips themselves. Low-density RAM is compatible with 100 percent of the system boards, while high-density RAM is compatible with only 10 percent. And if you use high-density RAM in a system that requires low density, either the system will recognise only half the amount of RAM installed, it simply won’t boot up or it may even affect the motherboard itself in extreme cases.
As always, it’s recommended that you consult the system board manual or the manufacturer’s Website for requirements and compatibility. However, we recently upgraded the RAM on an ASUS P4P800 Deluxe system board, going from 1GB to 2GB, and there was no mention at all of high-density versus low-density in the system board manual. High-density RAM is generally cheaper, so that’s what I went with. The system refused to boot up and the BIOS and the OS failed to recognise the installed RAM; the system was obviously not among the 10 percent compatible with high density memory.
We do suggest that if you are upgarding the memory that it’s something to be aware of.