What's eating a gig of RAM?

Question

I have the new aluminum iMac with 4GB of RAM. On a fresh startup, I have about 3.39GB of ram. After a day or so, that will drop down to about 3.2, then 3.11, then 3, then under 3. Even when it is sitting there not being used, everytime I wake it up I always have less RAM, but what gets me is the fact that I only have 3.39 when I first bootup. Does leopard eat 700MB of RAM on startup? I have 4 login items I believe.
iTunes helper
microsoft AU daemon
speechsythesisserver
system events
I have looked at activity monitor and don't see anything extrainious running, but I could be wrong. I have 2 widgets, iStatpro, and the default weather one. I also have an external hard drive always connected and turned on, but not using time-machine.
Just wondering where almost a gig of ram is going and if this is normal.

Answer 1

abeas wrote:
Just wondering where almost a gig of ram is going and if this is normal.
What does *Activity Monitor > System Memory* say?
If the "Wired" + "Active" segments aren't growing mysteriously, there's no
reason for concern.
Be aware that "Inactive" memory is essentially the same as "Free" memory,
except that the OS happens to "know" what it contains -- so it need not
be re-fetched from disk if some app asks for it. As long as the memory
would otherwise be idle, it costs nothing to keep the the data handy --
but only until some process has a better use for the memory space.
For example, if I power-up my iMac and run an app that reads a 1GB file
from disk, it takes 15-20 seconds to fetch the data. However, if I close
the app, and then immediately re-run it, the second "read" of the same
data file takes less than half a second -- because the OS "remembered"
that the file contents were already in "inactive" memory.
OTOH, if I load/run a bunch of other apps that need that memory space,
the OS "forgets" the old data and allocates memory from the "inactive"
pool -- in exactly the same way that it would allocate "free" memory.
...unix is your friend,
Looby