How is CPU speed calculated?

[narutodude000]

My CPU is Intel Core 2 Duo Processor 1.8GHz, that means that my total CPU speed is 3.6GHz right?
I went on eBay to look at laptops. I found a laptop with 2 3.3GHz processors (6.6GHz) which is much more expensive than a laptop with 4 2.6GHz processors (10.4GHz). Why is this? Does the number of processors affect the speed of the computer?

Edit: Also, is a 3.3GHz Intel i5 better or is a 2.8GHz Intel i7 better? If the i7 is better, why?

[svidgen]

It's not as simple as totaling up the core speeds. While you do increase number of calculations per second by adding cores, those extra calculations can't necessarily be taken advantage of in the same way. Each individual thread is still capped by the speed of an individual core. So, taking advantage of additional cores can often times depend on programmers to program with multiple cores in mind -- and assumes that the overall process can be split into multiple threads.

In terms of the higher clocked i5 versus the i7, my guess is that the i7 offers greater memory bandwidth, which can provide a significant performance increase in some scenarios. Though, not all users will necessarily see any increase. You should check benchmarks between the two processors: focus on a benchmark that tests applications you'll tend to use a lot.

[Big O(1)]

I can tell you that the i7 is more expensive for a few reasons. It has hyperthreading and a larger cache. Cache is very underrated in CPU performance because it's not understood well enough. Think about it this way. If I'm making a salad in my kitchen, some of my ingredients are right there in front of me (cache), some are in the fridge (RAM), and some I don't have so I will have to go to the store (hard drive). If most of my data is in cache, I will save a lot of time by not having to travel to RAM to get the data I need.

[narutodude000]

Ok thanks, that explains a lot.
Another quick question, does CPU dramatically influence browser speed?

[insafeuste]

Great analogy by svidgen. As mentioned above, the core i5 does not have hyperthreading enabled but the i7 does. Because the processor cores on the i7 can essentially process two threads simultaneously, a quad core i7 is recognized by your operating system as having 8 cores. Keep in mind though, that not all programs are written to take advantage of this feature.

To answer your question, because browsing the internet is such a low overhead activity, your processor would have to be archair for it to truly slow down your experience. You would see no difference between browsing the internet on a core i5 or core i7 processor, as both of these processors would be heavily underutilized either way. If browsing is currently slow, it is much more likely that the bottleneck is your internet connection speed.