Performance comparison of dual core and quad core processors with same TDP
A fact is that the 'cores' (or pipeline) are only a small portion of the CPU. If you open up a CPU you will notice that more than half of the 'real-estate' is spent on cache. There are many other parts that exists both on quad core and dual core CPUS and I will let you on a small secret, on many dual-core CPU chips there are actually 4 cores, 2 are disabled. Why is that? many times it is because there are production errors on some of the CPU sections (You really didn't think that they can print billion transistors with no errors did ya) and on some cases cores are just disabled due to marketing decision as it is cheaper to disable a core or two than to set up another production line.