Moderator-80-
Bezalel-
bombmaniac-
“Moderator-80” is correct. The hardware manual for that model does specify four memory slots.
Here’s the link to the manual page, select the “Hardware Replacement Guide”:
http://123.127.211.194/us/en/UserGuide/Guide_list.aspx?CategoryID=87378
I remember that there was/is certain memory type that required matched pairs, but for most memory types, the only requirement is that all the memory modules should be the same speed.
Also, if you have different sized memory modules, the larger one should go in the first slot, for efficiency’s sake.
(This is something I learned several years ago – as far as I know it’s still up to date.)