The board is supposed to support 100/200, 133/266, and 166/333.

So a setting of 133 and a multiplier of 16.0 should give you the proper speed? or 166 x 13.0

In the BIOS, do you have those settings as an option?

It sounds as if your setting is 100 x 11.0 which would be right for a Duron (Sempron?) processor. Where I have seen boards that support the Athlon and the economy processor the default setting is usually for the inferior processor and you get what you are describing.

Also if you have a PCI soundcard, have you disabled the onboard AC97 in the BIOS?

There is also the slight possibility that the new board is defective?