3.0GHz, 4000MHz system bus, 2MB L2 cache

Cache refers to a small chunk of fast memory located on the CPU die, it tends to come in two or three levels and lets the CPU keep information that it needs quick access to on itself rather than waiting for the relatively slow RAM.

All CPUs have L1 cache which is right next the CPU, its quite small but very fast, they also have L2 which is quite a bit bigger and also still very quick, then some have L3 which is usually a few MB, its slower than L2 cache but a lot faster than getting something from the RAM.

The system bus refers to the CPUs connection with the various components on the motherboard, a 4000MHz system bus implies to me that you are looking at one of the newer AMDs in which case it is called hyper transport, which is very similar to the Front Side Bus on older intel systems. The frontside bus on older systems refers to the connection speed between the CPU and northbridge.

Thank you hunter315 i kinda understood that