Mysterious Motherboard

Patricia’s computer needs more memory. It’s got half a gig, but it’s being brought to its knees. The board’s about four or five years old (I think it’s running a 1.8 MHz Athlon). It’s got an extra DIMM slot, but I don’t know how big a stick it can take. I can’t find the mobo manual, but I figured I could find one on line. The only identifier I can see on it says “Micro-Star Model MS-5390.” But when I do a search on that, I come up empty. I assume that it’s an MSI, but that model number doesn’t seem to exist in their data base. Anyone have any idea what’s going on? What are the chances that a board of that vintage can’t handle a gigbyte stick? I don’t want to go out and buy one unless I know it will work. On the other hand, just adding another half a gig would probably solve her problem.

[Update in the late afternoon]

Well, after reviewing the options (buying half a gig for sixty bucks or a full gig for a hundred and ten) and realizing that the memory I was buying would probably be useless on the next upgrade, I decided to bite the bullet and upgrade now. Athlon 64 and a gig of DDR2 for ~$250. I can use the other mobo for a development linux box.