I have an older motherboard with 4 simm slots and 1 dimm. I wanted to upgrade the ram by adding a 64MB sdram module to the dimm socket, but have heard that the PC100/133 types doesn't always work on older motherboards. The motherboard manual says that it takes 64/128MB SDRAM etc but no comment on the speed or anything else. Anyway, I have now tried a 64MB PC133 module and the computer works quite happily, but with only 16MB being detected. Could anyone shed some light on the situation? John Hilton System: Pentium 166 PC-chips M520 (or similar) mobo, i430VX chipset Visit our website regularly for FAQs, articles, how-to's, tech tips and much more http://nospin.com - http://nospin.org