Just found this... quite helpful in explaining clock speeds at least
Judging computer performance by GHz alone is a common misconception.
The clock speed of a CPU (the GHz) has nothing to do with relative performance of the processor... except when comparing it to other processors in the same product line.
What I mean here is that you cannot compare a 3.0 Ghz Intel P4 to a AMD processor or PowerPC processor - the Ghz means nothing at all...
However, if you compare a 3.0 Ghz Intel P4 with a 2.8 Ghz Intel P4 - THEN you have a valid comparison. The higher clock rate will be generally faster than the lower clock rate. (note that there are workloads where this is not true).
Now, more about the misconception - there are a lot of other factors that affect performance in computers. Processor speed is only one of them. Memory speed and architecture, internal bus speeds, storage technology, and software (OS and application) all contribute heavily to the perceived speed of a computer.
If you take a look at some of the performance-related websites (such as ww.spec.org), you'll see that computers with different CPUs handle different workloads better than others.
A good example for comparison (for an average consumer) is comparing a desktop to a laptop computer. I'll say now that desktops are generally faster than laptops, even at the same clock rate (Ghz). Why, you ask? Well, it's the other components that make the desktop faster. Typically, the disk in a laptop spins at 4200rpm (some are 5400 rpm), where a typical desktop has a 7200 rpm drive. The CD-ROM in a laptop is typically slower than what you find in desktops also.
The idea here is that it doesn't matter how fast the processor is, if the processor is sitting around twiddling it's thumbs while it waits for data from the hard drive/network/memory/whatever.
When it comes to pure speed of the processor, there are several definitions of speed... again, it relates to workload. For example, there's Integer Math speed (see the SPECint2006 benchmark at
www.spec.org), Integer Math Rate (throughput - SPECint_rate2006), Floating Point Math speed (SPECfp2006), and Floating Point Math Rate (SPECfp_rate2006). Processors that are great at Integer math may stink at floating point, and vice versa.
Some CPUs are made with bigger, badder math capabilities, others with better I/O throughput. Your choice depends on what you want to do with the computer, and are getting less and less every day as proprietary CPUs (such as PowerPC, Alpha, SPARC, and PA-RISC processors) are dropping by the wayside in favor of cheaper, mass-market Intel and AMD CPUs that are considered "good enough" these days.
About your comment about multi-core CPUs (quad-core vs. Dual-core vs. single-core)... The clock rate is important only if you run a single-threaded application. Such applications will run on only 1 of the cores, and will make a quad-core 2.4Ghz CPU look slower than a single-core P4 @ 3.2 Ghz.
These days, we often do a few things with our computers at a time (download a file, fetch our email, surf the net, etc.) so even a desktop user will see some benefit from a multi-core architecture because it can do more than one thing at a time. The single-core CPU can only execute one program at a time, where the quad-core can execute 4 at a time.
So, being able to execute 4 programs simultaneously at 2.4 Ghz vs. 4 programs one at a time (well, timesliced, they appear to run at the same time) at 3.2 Ghz - you're likely to find that the quad-core gets more done in the same amount of time - so it's "faster", even though it has a lower clock rate.
You can equate this to you and your friends running errands... let say that you need to go to the Supermarket, Sports Authority, Best Buy, and the liquor store - and each are in a different direction from your home (one is north, one is east, one is south, and one is west). You could leave your friends at home and go to the supermarket, then to Sports Authority, then Best Buy, then the Liquor Store OR you could send 3 of your friends, each to one of the stores while you go to the Supermarket. Which will be faster? Sending your friends, of course.
Now what about if you have only one errand to run... just the supermarket... going yourself is the only choice, and your friends will just have to wait until you get home with the chips. ;^) The additional "cores" (your friends) are no help when there's only one thing to do.
You're probably just as confused as ever (maybe even more so), but I hope this helps in some small way.
Good luck!!!
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