I think the link to the memory benchmarks was pretty direct. Depending upon the quality of your PC100, you may be able to run it at 133MHz. If you already have the RAM, try it. If you don't have the RAM yet, and want good performance, buy some good PC133. The KT7, like the KA7 is a performance mobo. Running PC100 in it to me is like running low octane gas in a race car. I just built a KT7/ 800 T-bird system yesterday. I put in a 128MB stick of Infineon PC133, and running at CAS2 turbo, 133MHz, it is on par benchmark wise with my KA7 Athlon system with the RAM running at 146MHz CAS2 turbo. Just my opinion on the subject.