Denis, I'm afraid I don't understand Cas or Density so would appreciate an explanation of these. The motherboard is a Rhino12 with 4 simm slots and one dimm. I had 4x4mb EDO and 1x32mb SDRam pc66 in it and all worked fine before. Donald, The Ram was not new. It was from a friend's Pentium 300. His motherboard is LX or EX, with a fsb of 66mhz but he had this 64mb pc100 module in it and he had no problems. Mark, I'm sorry for messing up the posts thing. I did find the Rhino12 site but the only information there was about jumper settings etc, nothing about memory. Julie _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com/intl.asp PCBUILD's List Owners: Bob Wright<[log in to unmask]> Drew Dunn<[log in to unmask]>