I'm trying to figure out what a buffer is in RAM, I'm currently learning about RAM and the different types. Could someone please explain to me the importance and purpose of a buffer in say DDR2 memory modules?
I think you are referring to unbuffered, buffered and fully buffered RAM. If not please clarify your post.
First, this is how basic RAM works:
Example: CPU want to read something from RAM and load it in a register
Now that is a simplified example. In praxis there are a few complications.
Also note that I explicitly choose an example where the data was read into an on-CPU register. Again, the data was copied from the bus to a place in the CPU. This might be a literal copy, or there may be a buffer at the 'edge' of the CPU where the data is copied to the buffer, and then from the buffer to a register. (Possibly because internal registers and external RAM use different voltages, and the buffer is used to work with both of them).
Instead of feeding the desired data directly from the memory chips output, it would be copied to a buffer near the DIMMs output. Memory modules which have this features are called buffered or registered.
Memory which lacks this is called unbuffered or unregistered.
are you sure you mean buffer, and not FSB/CPU-side cache?
if so, see here for a detailed coverage of Disk IO caching/buffering in ram.