If it's an A64 it's 9 multiplier by 200 mhz fsb, which is 1800 mhz effective, not 13x166. As for overclocking, there is a stickied thread at the top of CPU/Procs forum which is helpful. What's the brand of your motherboard, or did you build your system?
Edit, you have a socket 754 mobo, googled it. Meaning that 3000+ is rated at 2 ghz instead of 1.8.