Why does my Vaio SA i7-2620M show 4 cores?

Take a look at this picture:

 

Hyper threading =)

 

More specifically, the i7-2620M (and most other new dual core processors) have 2 virtual cores in addition to the 2 physical cores they have originally. This technically makes it a 4 core processor but is still more accurately described as a 2 core since there aren't many applications that utilizes hyper threading...

 

Yes, what they say before. Actually most new mid to high end processors will have Hyper-Threading. Some lower end processors wont. Some i3's dont have them as well as the new Sandy Bridge Pentiums... which confuse the heck out of me.

 

As someone who has owned computers with and without Hyper-Threading (and ran some benchmarks to see how useful it is), I can say it's a really good thing.

For heavy multi-threaded tasks, it can improve performance by around 30% or so (vs. having it disabled).

 

LOL The dual Xeon quad core servers I work with (two physical processors, each quad core) show 16 CPUs. Task Manager looks awful.

 

since when did applications need to support hyperthreading? even OSes don't need to be aware of hyper threading for it to work(although the system is smarter about CPU allocation if it is).

 

If an application only uses one thread to do all its processing, multiple cores and/or hyper threading will not produce any performance benefit for that app. An OS typically spawns multiple threads.

 

i didn't say any of that. He said that an applications needs to support hyperthreading in order to use those hyperthreads.

I'm saying that as long as the app supports multi-threading, it will use them.

 

No arguments there. Hope this discussion has cleared things up for the OP.
Hyperthreading == good.
Multiple cores == even better.
Multiple cores + hyperthreading == awesome.