3.0ghz? I don't think there's any way under the sun my 3000+ would hit those speeds. If it did I'd be well chuffed!
Unless that is you're refering to the Intel clock speed equivelant
As for the CS:S benchmark, you're saying the score doesn't deviate on high or low settings? Um... are you sure you clicked 'Apply' after changing the settings?. Source's framelimit isn't capped, as far as I know, at least not by default.