esrever :
if its impossible to implement threads spread across cores. How come quad cores are better for gaming than dual cores now and wasn't the case 4 years ago?
Again: LISTEN.
What I've said, many, many, many times now, is this: Developers do not, and will never, hard lock threads to cores on any architecture where you can be prempted by other threads (read: all non-integrated Hardware). The scheduler, not the user, tells the CPU what core to stuff a thread on, and the scheduler, not the user, tells the CPU what thread to run.
Secondly, the overwhelming majority of games are going to run with dozens of threads [they have been for decades], but only 2-4 will do any real amount of processing power, and of those, only 1-2 are able to be run in parallel, and even then, only for small periods of time (example would be the Render thread, which executes fairly late in the processing cycle).
As a result, scaling quickly hits a brick wall.
Remember the E8600 versus Q8xxx debates? How a faster clocked Duo almost always beat the slower clocked quad? Same basic principle applies.
And why is it that some games get half the fps when running a dual core compared to a quad core?
Examples would be nice, preferably on the same CPU arch (none of this i5 versus BD nonsense; give me i3 versus i5 if you want to do a "proper" duo versus quad comparison). In all but a handful of cases, i3's perform close to their big brothers, the i5's. The general exceptions are multiplayer (which makes sense, since you add a relatively process heavy thread to the mix), or games with more advanced physics engines (PhysX, anyone?).
I'm not saying quads don't help to some extent, but for the majority of games, an i3 is more then sufficient. In most cases, you run into a brick wall in terms of scaling after 3 cores or so.