Wrong!
AvoK95 wrote A 3GHz single core is slower than a 1.8GHz dual core.
This is
almost true, but it's not correct. Multi-core only means more processing units are available.
yasamoka wrote3 x 1 = 3, 1.8 x 2 = 3.6, 3.6 > 3, so (1.8 x 2) > (3 x 1).
This is just plain wrong. A dual-core at 1Ghz is
not equivalent to a single core 2Ghz.
Why do cores matter?
To explain what's the advantage of multi-core systems, let me make a (bad) analogy.
Imagine two competing sandwich delivery places in Beirut. The first one has 4 drivers but they're all a little slow. The second one has only one driver, but he drives a Ferrari.
Compare these two tasks:
- Task1: Deliver sandwiches to 8 different places all in Beirut.
- Task2: Deliver only one sandwich to Akkar, over 100km away
No matter how fast the Ferrari is, it cannot deliver to 8 different places in Beirut faster than 4 other regular cars working together. However, for task2, it's a whole different story. Being 4 gives no advantage at all for a single long trip. Especially against the Italian monster.
How does it work for CPUs?
It all comes down to the software you're running. If the software is written in such a way that it can be divided into small independent parts, it takes more advantage of multi-cores than the ones who aren't. Unfortunately developers are slow to adopt the (relatively) new habit of writing software that runs in parallel. Does it mean that parallel software is rare? No. It just means that there are a lot of monocore programs out there.
It also means that a single core 3Ghz can be better than a 2Ghz dual core at certain things. No matter how much you divide your program, at the end it's running on a single core. And sometimes you need it to be faster.
What should you buy?
Common apps (browsers, media players) and serious games are already parallelizing their processes on all sorts of hardware. Unless you have a good reason,
you should always prefer multi-cores.
If you have specific software to run, make a background check. You might be more interested in clock cycles than the number of cores.
Note
Modern laptops are more complex than the simplistic scheme I expose here by several orders of magnitude. All sorts of hardware components with all sorts of features come into play. It's insanely complex as well to predict accurately the behavior of a software on a given laptop until you actually run it.
