Not at all. It depends on the cache design and the CPU clock speed (assuming you mean CPU cache). In some cases (such as the Core 2 series CPUs, if I'm remembering correctly), the CPU cache speed is the same as the CPU core speed. In other cases, such as the Core i7 and Phenom II CPUs, some of the cache runs at the same speed as the CPU core (L1 and L2), while the larger L3 cache runs at a slower (though still quite fast) speed that you can set separately. In all cases though, the speed of the cache is independent of the RAM speed.