Front Side Bus Speeds?

I am currently trying to better my knowledge of the hardware and intricacies within those. My first challenge was actually trying to understand what "OVERCLOCKING" actually means down to a qualitative level.
So typically you overclock a CPU to "communicate" faster with other parts in the computer (at least this is my understandering of the process).
After reading this article: How to Calculate Computer Bus Speed | eHow.com
I says to determine the speed of you're PCI bus, and according to ehow if you are running a FSB of 133 MHz/4=33.25 pci speed or 166/5=33.20 speed? How does that make sense and the AGP bus is x2 (66.4 & 66.5)? They are virtually identical speeds even with overclock? OR am I looking at this horribly wrong?

 

1) At a very simple level... when you overclock a CPU, you're increasing the clock speed of that CPU. The clock speed is directly related how fast that CPU is, and how fast that CPU performs calculations. The higher the clock speed, the most calculations it does.

Imagine you work on a factory assembly line, and can assemble 3 automobile transmissions per 8-hour shift. If you drink a bunch of caffeine, you start working faster, and can now assemble 4 automobile transmisisons per 8-hour shift. You essentially just "overclocked" yourself by increasing the amount of work that you can do in a given amount of time. This is basically the same as CPU overclocking - you push the CPU to do more work-over-time by increasing the rate of work.



2) Overclocking may not always give you actual real-world performance gains. Computers are very complex, and require several different parts and sub-systems to work together. Increasing the performance of a single component will not necessarily increase overall performance.

For example, game performance is typically bottlenecked by the GPU (video card), and not the CPU. Similarly, most applications are bottlenecked by the hard disk drive, and not the CPU. In those situations, overclocking the CPU will have practically zero benefit to your performance. Only in a very specific handful of situations will you find a direct correlation between CPU speed and actual real-world performance.

But many poeple will still overclock, because: 1) You get additional performance out of your hardware without paying additional money; 2) It's fun.



3) For purposes of the M11x, you don't need to worry about all of that PCI bus / AGP bus stuff. You will find that stuff on desktop computer motherboards with overclocking features, but don't need to worry about it on the M11x.

If you own an M11x R1 (Core 2 Duo CPU), then your BIOS only has the option to turn Overclocking on/off. If you own an M11x R2 (Core i5/i7 CPU), your BIOS has the option to set your overclock from 133MHz --> 166MHz. Be aware that overclocking is very dependent on luck. Some people are lucky, and can overclock their M11x R2 all the way up to 166Mhz and still have a stable computer. Some other people are unlucky, and can only get their machines to be stable at 140Mhz.


4) All of that stuff that you had posted about FSB speeds of 133Mhz, PCI speeds of 33.20Mhz, AGP speeds of 66Mhz, etc... it all goes back to how computers are comprised of several complex sub-systems all working together (CPU, memory, PCI cards, PCI-E cards, etc). In order for those systems to all be synchronized and work together, they need to use the same master clock (but not the same clock SPEED - this is important).

Using that automobile factory example before... the "master clock" is like a Shift Foreman. The Shift Foreman is responsible for telling all of the different assembly lines when to start / stop their shift. Now, each assembly line team may work at different speeds... your automobile transmission team may make 3 transmissions per 8-hour shift. Another team might make 7 steering wheels every 8 hours. Another team might make 14 car seats every 8 hours. All of these teams (computer sub-systems) might work at different speeds, but it is important that they all use the same Shift Foreman (master clock) to tell them when to start/stop their work shifts, so that the entire factory (computer) knows when to start/stop each work cycle.

In this example, let's just assume the Front Side Bus is the "master clock" running at 133Mhz.

So:
* Front Side Bus ticks along at 133Mhz (133,000,000 times per second).
* CPU runs at 2.66Ghz clock speed. It does this by using a clock multiplier of 20x (20 * 133Mhz = 2.66Ghz). This CPU's clock speed is 20x faster than the "master clock" of 133Mhz.
* PCI is rated to run at 33Mhz. It does this by using a clock divider, and dividing the master 133Mhz clock by 4 (133Mhz / 4 = 33Mhz).
* PCI Express is rated to run at 100MHz. It does this by using a clock divider of 4/3, and dividing the master 133Mhz front-side-bus clock by 4/3 (133Mhz / (4/3) = 100Mhz).

When you overclock a CPU, you can overclock it by either adjusting the clock multiplier or the front-side bus. However, just about every CPU locked the clock multiplier, and didn't allow you to change it (our CPU would be locked to a 20x multiplier). That means the only way to overclock a CPU is to adjust the front-side bus (the "master" clock). But when you do that, you also overclock all of the other components (PCI, PCI-E, memory, etc) that rely on that front-side bus (the "master" clock)... and that is not something that is always desirable. So, overclocking motherboards let you tweak the clock dividers , so that PCI always runs at 33Mhz, and PCI-E always runs at 100Mhz. If you overclock your front-side bus from 133Mhz --> 166Mhz, your PCI clock divider would adjust from a divider of 4 --> 5 (because 166Mhz / 5 = 33Mhz, the rated speed of PCI).

 

Wow, it make so much sense now thank a lot I'm sure it too a bit to write, I really appreciated it. +Rep'd

 

Nice write up. It's one of the best ones I have seen, good job!