The only thing that I know of that can tell you the pci/agp clock is an oscilloscope (or however you spell it).
Some people will tell you that using turbo1 will make your agp/pci clock very close to spec, but these people are all going by what 1 person posted on Hardforum.com. The name of the person is "ase" that started the rumor that turbo1 locks the clocks, this person has 8 posts total, so I am very sceptical.