In this guide, I will explain why many eBay sellers are misleading you when selling computers, advertised as "Quad Core 10.6GHz" etc...
Intel & AMD both advertise their dual & quad core processors as the speed of one of the cores in the processor. A few examples are, an Intel Core 2 Duo E8500 runs each of it's two cores at 3.16GHz. An AMD Phenom X4 Quad Core 9950 runs each of it's four cores at 2.6GHz. However, they do not say it is a 6.32GHz dual core or a 10.4GHz quad core processor.
This is because dual & quad core processors do not combine their cores to run a single application at the speed of the 2 or 4 cores added together. This is where the missleading begins, ebay sellers list computers as twice or four times their clock speed, which is incorrect. The Core 2 Duo E8500 runs at 3.16GHz per core, but never at 6.32GHz!
The people selling a computer or proccesor which is running faster than 3.16GHz (This is the fastest stock speed of any Intel or AMD processor as of July 2008) are misleading you or overclocking the processor; which voids your warranty.
But, do not let this put you off buying a dual or quad core computer, there are honest people out there like myself who give you the real information and specifications! A 2.4GHz dual or quad core processor is still alot faster than a 3.8GHz single core processor, as they can do more work per clock cycle. Another benefit of using a dual or quad core processor is that alot more software is being developed to use the two or four cores at once, specificly games or video conversion software, these are called multi threaded applications.