"Actual bus speed is less. Listed bus speed represents the equivalent effective throughput for data." Wait, say what??

"Intel's mobile processor gets even better with the next generation, 64-bit enabled, Intel(R) Core(TM) 2 Duo processor T9300 featuring 6MB internal L2 memory cache, a 2.50 GHz dual-core processor, and a 800 MHz front side bus. Experience increased system responsiveness and longer battery life when combined with the Intel(R) PRO/Wireless Network Connection to get the Intel(R) Centrino(R) Duo mobile technology solution you have been waiting for! DISCLAIMERS: The Intel Inside(R) and Centrino(R) logos, Celeron(R), Pentium(R), Centrino(R) are registered trademarks of Intel Corporation. Dual Core is a new technology designed to improve performance of certain software products. Check with the software provider to determine suitability. Not all customers or software applications will necessarily benefit from use of this technology. Actual bus speed is less. Listed bus speed represents the equivalent effective throughput for data. GHz refers to internal clock speed of the processor. Other factors besides clock speed may impact system and application performance. Intel's numbering is not a measurement of higher performance. Processor numbers differentiate features within each processor family, not across different processor families. See http://www.intel.com/products/processor_number for details. This system requires a separately purchased 64-bit operating system and 64-bit software products to take advantage of the 64-bit processing capabilities. Given the wide range of software applications available, performance of a system including a 64-bit operating system will vary."

So what in the name does all this mean? Basically, I ordered an 800MHz processor for....nothing?? Sucks when you start figurin this kinda stuff out AFTER you just spent $1600.
Can one of you computer educated prophets out there tell me to your best ability what "Actual bus speed is less. Listed bus speed represents the equivalent effective throughput for data." means??

Source: www.hp.com

 

4 x 200 Mhz = 800 Mhz effective.

 

Probably implies the actual FSB verses the QDR FSB.

Edit: Ninja'ed!

 

It's just the way Intel's bus is designed. It's like DDR memory. The effective speed of PC6400 memory is 800MHz, but since it's DDR, the actual speed is 400MHz.

Intel's bus is rated at 800MHz, but because of the way it's designed, the actual speed is only 200MHz.

EDIT: 2x ninja'ed

 

http://en.wikipedia.org/wiki/Quad_Data_Rate

 

Sure, it means that clock speed is basically irrelevant. The FSB is actually only 200MHz, not 800. They just do a couple of tricks so it effectively gets quadrupled. One of them is running dual-channel RAM. Two channels means twice the throughput, so for convenience, let's call the FSB 400MHz instead of 200. I can't remember where they get the other doubling from, might be from the fact that DDR RAM transfers data twice per clock cycle... Or then again, it might be something else.

But strictly speaking, the FSB bus only runs at a 200MHz clock (a quarter of the listed value)

This is similar to your RAM, which also internally runs at a far lower speed. (DDR400 actually runs at 200MHz internally, just like DDR2-800)

What it means is simply that internally ,the FSB is only 200MHz, but because of a bit of trickery, the throughput is just as big as if it'd been a 800MHz bus.

Think of a highway. Does 4 lanes instead of 1 mean you get to your destination faster? No, it just means that 4 times as many cars can drive there without having to queue up. On average, if you look at traffic per week, say, more lanes means that far more cars can get through. But for the individual car, it doesn't speed things up.

 

So, does that mean it has plenty of room for overclocking???

 

Don't worry! And you did not just buy a 800Mhz processor ( I hope, ), just a standard disclaimer.

 

So, does that mean an 800MHz isn't any faster, but can multitask a lot better since it has more "lanes" ??

 

thats probably why the battery life is so good excluding the enhanced speed step technology

 

It's 800MHz, because it's carrying 4 units of data per 200MHz clock cycle. All Intel FSB carry 4 units of data per clock cycle. So clock speed can be used to determine the relative speeds of various Intel buses, because the architecture is all the same.

Therefore, an 800MHz Intel bus will indeed be faster than a 667MHz Intel bus, even though neither of the buses are running at the "rated" speed.

 

Do not forget that the 800Mhz is the BUS SPEED, not the processor clock speed. The clock speed of the processor is still 2.5Ghz on each of the two cores.

 

So can I (as a computer nub) ask what the difference is between the bus and processor speed? And also, what is the tasks/responsibilities of each? (sry for all the questions, just trying to learn a thing or two)

 

The processor speed is a relative measure of how quickly a certain type of processor can process information. The bus speed is a relative measure of how quickly the processor can communicate with the rest of the system (ie memory or chipset).

I say "relative" in both cases, because different processors and buses will offer differing levels of performance at the same "real" clock speed.

 

Well written, thnx for the intelligence

 

Yes you can, and I will do my best to explain well but keep simple. If we make make bricks out of clay. The FSB brings you the dirt, say 800 lbs per hour. Well the CPU has to make that dirt into clay bricks, clearly much more work so you need it to be faster than the FSB as it does much more. If either is more efficient than the other the brick production is not increased by the one over producing so yo need balance, the slower of the two is called the "bottleneck". Now as I have said the CPU must do much more than the FSB to create these bricks, so you need it to be faster. But to complicate this beyond what my example can demonstrate. Synchronization is important meaning if for example the CPU has to wait for the dirt that can slow down the whole process. So faster FSB is usually better, and then once CPU gets the dirt of course the faster the better. I think!

Edit: I type slow, Commander Wolf good explanation I might delete mine!

 

i thought it was the northbrigde that did all the work of the fsb and the is where the bottleneck starts

 

The Northbridge is another chip on the FSB. The Northbridge connects the processor to the memory and the PCI/PCIe channels through the FSB.

If the processor is requesting a particular type of clay from the warehouse that is the memory, it will send a messenger along the FSB to alert the NB to withdraw this clay from the memory. The NB will subsequently send the clay along the FSB back to the processor.

No need; it's a genius analogy, I'm sure

 

Depends on how you define "faster".
An individual byte of data doesn't arrive any faster, but the bus can have 4 times as much data in flight at once. So if you look at how much data gets pushed through per second, then it *is* faster.

This is where the analogies start to break down, because clock speed really have nothing to do with latency. The clock speed is simply the "drum beat" that synchronizes all activity. 200 million times a second, the drum beats, and each time, the bus loads or offloads data. The width of the bus determines how much data is loaded or offloaded, and because of a bit of trickery, this can actually happen two or four times per beat.

But all of this only determines the throughput. Of course, the more often the bus leaves, and the more passengers it can carry, the more passengers end up at their destination per hour.But the clock speed only determines when the bus departs, not how fast it drives.
The speed at which it drives is a completely different beast. (That's the latency, and I don't believe there's any reliable information on that, and it's pretty much independent of clock speed and all other factors)

If you only listen to the drumbeat, then your 800Mhz bus is exactly the same as a "plain" 200MHz bus.
But if you take into account what actually happens between drumbeats, it gets 4 times as much work done.