Hi, I have a jetway 542c mother board. I have 2 sticks of pc133x128 dimm. It is dimm that is OK in a pc100 system. When I do a memory upgrade search for this board it says to use pc66 memory. I see my new hard drive is ultra DMA100 capable but board has only ultra DMA33/66 so HDD is running at 66. I have a AMD K6-2x500 CPU with FSB at 100x5. I thought the dimm should match the FSB or is that wrong? Why do they only recommend pc66 dimm? Is it because of the DMA66 speed? Will running pc 100 dimms cause problems? I wanted to get a pc100x256 dimm to replace one of the 128s but now I am not sure if I have the right speed dimm in it. Confused Tom