it depends on the game. some are cpu bound while others are gpu bound.
it really does depend on the game and thats why i always say build a balance system. a decent dual with a low mid gfx card will give just as many fps all be it at lower rez asa high end quad with high end gfx... but more often than not if you put a low end dual in with a high end gfx you will get cpu bottlencks even with an i3 2100 you can still bottlneck with a 570 or 5870 on quite a few cpu bound games.
as hexit said, if they have every game get same performance only based on CPU while completely disregarding game's engine and design then they are lying to you. If you wish to believe one source only, be my guest, however, I would think most people prefer to think for themselves.
some games are not optimised to use multi core cpu's, for example skyrim gets no benefit of running on a quad vs dual core. On the other hand game like SC2 gets a big difference depending on how many cores you got and what architecture they use. Skyrim is very CPU bound while SC2 is both CPU and GPU bound.
Doing benchmarks with varying CPUs while keeping everything constant is useful, but be critical of the results they give you. Ask yourself do they make sense.
I agree with HEXiT.
It depends on the game.
Suppose the game utilizes all four cores of a CPU, it would definitely run that game well, compared to a dual core CPU even if it has higher clock speeds.
Some of the older games, such as those which only utilizes two cores, will run better on a dual core CPU with high clock speeds than a quad core CPU with lower clock speed.
There you can see the e6850 beating the q6600 which is clocked considerably higher than the q6400. Most games will mirror these results, and in single threaded applications the difference will be even more pronounced. You will absolutely regret buying a q6400 to game on.
i dunno where you heard that, and you do know that list is over 3 years old and not only that it doesnt take into account crysis being badly optimized for quads so the benchmark is irrelevant sorry!... but there are a lot of quads in that list above the e6850 that being said the e6850 is still classed as an enthusiast cpu and still is priced accordingly... ie 300 pounds... why the hell would you buy that today when you could buy a 3.0 quad for less than half that... and i guarantee the quad will match it in single threaded performance. in fact i know my firstname.lastname@example.org will murder it and it cost 200 pounds.
back in the day your argument would have made sense but in today, it just doesnt.
sadly tech must move on and by the looks of it , it has left some behind.
as a basic rule of thumb. any 2.6 amd quad and any 2.4 intel quad will be enough for gaming for at least another 2 years or until they release the new consoles.
the q6400 is pretty much the lowest you want to go, and i personally wouldn't touch it as there is better quads out there for less/same money.
There are always processes going on in the background that windows can run on the cores that a game isn't using, so if a game is programmed for 2 cores it would probably still run a little better on a quad core at the same speed because those background tasks won't be bogging down one of the cores the game is trying to use. But when the difference is 3.0 vs 2.13 (a 40% difference) then having background tasks moved to the extra cores isn't enough to make up for the loss in clock speed.
Not all cores are created equal though, a q9 series at 3.0 ghz is going to be faster than a q6 series at 3.0 ghz even though they are both quad cores because the 9 series has 12 mb of L2 cache vs 8 on the 6 series. All chip series have achetectural differences so you can't directly compare GHZ of one line of chips to another line.