Don't expect miracles with game performance on Core i7 CPUs. Some titles will get a performance boost of 10 to 15 percent, but most of them will get less than 10 percent.

The big issue is that games cannot take advantage of four cores and Nehalem / Corei7 has four physical cores and eight threads when it uses Hyper-threading. Games simply cannot take advantage, as it’s very hard to make a code that can run eight threads simultaneously and if you do that, all CPUs with four or two cores would end up being slower on such an engine.

This might become a real problem for Intel in the future, as the future of CPUs is multi-core / multi thread and if the gaming industry cannot put four core in use, what will happen with sixteen and thirty-two cores that might come in the next few years?

In most contemporary games you won’t see any noticeable difference in frames comparing dual-core Intel at 3.0GHz and Quad-core Intel at the same speed, you might get a few percent; but not enough to justify a saucy investment in quad core.