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Fsb?

A

Atrye

Limp Gawd
Joined
Sep 11, 2004
Messages
222
I'm so confused... :confused:

How do the 800MHz FSB on the Intel chips compare to the 266/333/400 FSB on the Athlon XP chips? I always hear about Intel's "quad-pumped" FSB... Does this mean that it's really a 200MHz FSB just made to look bigger and the 400FSB on the Athlon XP is twice as fast?

Also... The Athlon 64 chips all say that the FSB is "integrated into chip." What on earth does that mean?? :confused:

Someone please help unconfuse me!
 
it's very simple if you look at it from terms of actual FSB...not the marketing stuff. Like you said, the P4s are 200 Mhz quad pumped. So, the actual FSB is 200 Mhz. Knowing that, you can see why you would have DDR400 for a system like that (200 Mhz Double).
 
the effective speed of the FSB for the P4C family is 800Mhz. and what AMD means by the FSB being integrated into the CPU is really the memory controller is now on the CPU instead of being on the motherboard. there are pro's and cons to this design. the pros is that this increases bandwidth greatly and there is much less latency in between the CPU>memory controller>RAM. downside is that if they want to add a new feature like say dual channel memory, AMD would have to produce a whole new CPU just to have that feature enabled. whereas with intel CPU's they just add the feature in with a new motherboard chipset which is much cheaper for consumers to upgrade. FSB stand for front side bus, this is the bus that the CPU uses to communicate with the RAM and the motherboard chipset. the faster the FSB, the faster data the computer as a whole will potentially be.
 
Soo... given what the first guy said... The Intel 800MHz FSB is really a 200. So the AMD 400 is twice as fast?

But this other guy says that the 'effective' speed of the Intel one is 800 (which is twice the AMD400). So.. I have a few new questions.


Why is the 'effective' speed of the 200MHz Intel bus 800Mhz?

And which FSB ends up being faster overall?
 
the AMD athlon FSB is 200 also. the two just implement it differently.
the AMD athlon Barton chips have a FSB of 200 which is double pumped to an effective 400Mhz.
the Intel P4 northwood chips have a FSB of 200 but are quad pumped to an effective 800Mhz.
so the intel FSB is in fact twice as fast as the athlon xp FSB which runs at 400Mhz.
the Athlon 64 FX series have the memory controller built into the CPU so that the controller can run just as fast as the CPU itself but it doesnt. i think the FX chips' memory controller runs at 1.6Ghz but i may be wrong. this allows the memory on the these chips to have a lot of head rooms for data transfer.
i hope this clears things up a bit.
 
Well... I'm slowly becoming less confused...

What does it mean to say 'double' or 'quad-pumped' ?
 
Atrye said:
Well... I'm slowly becoming less confused...

What does it mean to say 'double' or 'quad-pumped' ?
Click to expand...

Think of the system clock as a sine wave. (I hope I haven't lost everyone already.) Originally, computers could only send data at the beginning of every cycle.

AMD figured out a way to transmit data in the middle of each cycle, as well, leading to twice as much data going through per clock.

Intel then came up with a way to transmit data, not just at the beginning and middle of the cycle, but at the top and bottom as well, transmitting 4 times as much data per clock.

*Note: the order may not be correct, Intel may have done theirs first, or they may even have been simultaneous, but the sine wave thing should be fairly close.*
 
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