You forgot to mention what CPU you have. Just re-read your title. It looks like you have the i5 750. Set the multiplier at 20. That might be enough to bring Turbo back. If not:
Have you explicitly set Turbo to Enabled, as opposed to just Auto? At Auto, the motherboard will disable it when you OC. Set it to Enabled. Also, I believe C1E and the C-states need to be Enabled. You may also need to Enable EIST. (On second thought, I don't think this is necessary for Turbo.)
If you have an i5 750, the multiplier needs to be at 20. If you have an i7 860, the multiplier needs to be at 21.