Would a single 10GHz CPU be as fast as a quad-core CPU with each core running at 2.5 GHz? I would imagine that the caches on the Four processor cores would give it a performance advantage over the 10GHz single core. The way CPU manufacturers went after the days of highly-clocked processors (Pentium 4) was to add more processors (cores) onto a single die, instead of having just One really fast core. Running a CPU at a speed of 10 GHz would be impossible with conventional cooling, and would probably require liquid nitrogen. Does adding more cores onto a CPU die increase thermal output? Is this why the more cores, the smaller the die, and lower stock clock speeds? Such as the next generation 6-core processors from AMD and Intel being 32nm instead of 45nm like the quad cores.