Hi!

Your system uses the Intel 815 chipset, which can accept PC133 SDRAM.
If you have PC133 parts to install, you should use them, as they will
provide the best performance and stability. (PC100 modules might not
be stable in your system, since they will probably be overclocked a
bit.)

You can install a maximum of 512MB RAM. Amazingly, high density
modules *are* supported. I've put a single 512MB PC133 modules in one
of my Deskpro EN systems and it worked fine. The system recognized all
the capacity.

The memory controller in these things is really pretty tolerant and
will happily take modules of mixed sizes. You don't have to pair them
up, although some performance gain might be seen if you can.

You can put more than 512MB RAM in place, but if you do, the BIOS will
tell you that you've installed too much RAM and must remove some of
it. (I think it might be possible to hack the BIOS and remove this
limit, but I haven't tried mainly due to lack of skill in this area.)

William