Barry, Plugging in the wrong type of SIMM will not harm the MoBo (but I've seen stranger things). In most cases, when a PC won't boot after an upgrade, it is usually a loose connection. TRIPLE CHECK every wire connector and make sure they are all plugged in good and tight. Even if you didn't unplug it, check it anyway. While working on the RAM you might have jostled and jiggled something else loose. Also check each and every board and socketed chip. Jim Meagher ===== Micro Solutions Consulting Member of The HTML Writers Guild http://www.ezy.net/~microsol International Webmasters Association 410-543-8996 MS Site Builder Network - Level 2 member ===== -----Original Message----- From: Barry Marx <[log in to unmask]> >I am trying to help a friend upgrade the RAM in a DECpc LPX 433sx that he >recently bought used. It is a 486 system with 8 MB Ram, and a Pentium OD >already installed. (We didn't have any documentation initially, although I >just discovered that DEC has the manual online.) > PCBUILD mailing list is brought to you by: The NOSPIN Group http://nospin.com