Memory Speed!

Hi, im running on a standard pc (see specs below) which is currently not overclocked as ive jst formatted it, bt i was planning to lower the memory timings when i realised that my memory speed was only at 166Mhz. Ive got a Crucial 400Mhz PC3200 512mb stick in there and i thought that runs at 200Mhz so i changed it in my bios, only for my system to then hang up and when i reboot it then says its only operating at 100Mhz! Im confused! Can some1 please give me a logical answer to this (and it hasnt been overclocked before!). Thanx.

*Solved it! Changed the slot it was in.

Default is 1:1 memory ratio at default speed which I think is 166 FSB with that CPU (2X166=333), so that's why the RAM is running at that speed. The RAM don't automatically run at what it's rated for. For your RAM to run at 200 frequency, you need to overclock the system to 200 FSB. Leave the ratio at 1:1 on AMD systems.