"Travis King" > wrote in
> Regardless who's right, they'd have to be cutting into performance at
> least a little... (right?)
> I always thought that the FSB you set the
> computer to was half of what was advertised. For example, I thought
> that when you set up a 333MHz FSB processor, you always cut it into
> half which would be 166.
Correct, you set your 'physical' bus speed to half the rated, or effective,
FSB speed. I've tried to explain this more below. Note that for AMD
Athlon64 and FX processors there is no FSB but there is a memory bus which
will be rated the same way that the FSB is rated. This is because for these
processors AMD has integrated the memory controller into the CPU.
> I've always wondered where the other 166 (or
> 167) goes...
It doesn't go anywhere. See below.
> Now explain why with a P4 800MHz FSB is supposed to be
> set to 200... Is Intel just trying to make it look like a giant FSB
> over AMD when it is technically the same, or does it have to do
> something with their so-called "hyper-threading technology"?
AMD does the same thing. It has nothing to do with hyperthreading. See
> probably a big reason why Intel processors don't perform much faster
> than AMD - because the actual FSB's the same. (If I recall right, the
> FSB is much more important to performance than the multiplier.)
Yea, they're effectively the same (FSB) ratings wise. But, by integrating
the memory controller into the CPU, AMD has significantly reduced memory
latency. Latency, for these purposes, is the amount of time it takes for
memory to return data to the CPU, once the CPU has begun asking for data.
There is a delay, so to speak, and AMD has reduced the delay in their CPU's
dramatically by integrating the memocry controller into the CPU. Intel
CPU's still have the memory controller integrated into the Northbridge
> have always bought AMD because Intel's prices can sometimes be double
> that of AMD's and perform nearly the same.
Some additional background information: Todays memory is typically 'DDR',
or 'Double Data Rate'. What that means is that the memory performs two data
transfers per memory access cycle, or bus cycle. Additionally, many (but
not all) modern memory-busses/motherboards/CPUs are 'Dual Channel' so that
there are two memory busses running in parallel. Therefore, since memory is
DDR, a 2X multiplication, and 'Dual Channel', another 2X mutiplication,
you effectively get 4X data transfers per bus cycle. So, whatever your
physical bus speed is, is multiplied by 4 to get an effective bus speed.
For example, a FSB speed (in the Intel world) or a memory bus speed (in the
AMD world) of 800MHz is derived from a physical bus speed of 200MHz
multiplied by four to account for DDR and Dual channel. In other words, the
bus is running 200MHz but your getting an 'Effective' bus speed of 800MHz
and so you see a FSB rating of 800MHz. This is not a gimmick. 'Dual
Channel' and 'Double Data Rate' produce real and significant memory
performance improvements. Both AMD and Intel take advantage of 'DDR' and
'Dual Channel' memory technologies. I have concentrated my
investigation of AMD mostly on Athlon64 and derivatives so you must see
what part of this applies to an XP3200+ yourself. Specifically, is it DDR,
and is it Dual Channel? Also check the motherboard spec's. Motherboard and
CPU spec's must be compatible. I guess there is a complication for single
channel CPU's. If your running a 200MHz bus you'll still want PC3200 even
if you don't have a Dual Channel system. If you just have DDR, then
multiply the physical bus frequemcy by 16 to get the PCXXXX rating you will
need to run full speed.
You must ensure that memory stick spec's, motherboard spec's, and cpu
spec's are all compatible. If you want to run PC3200 the CPU and/or memory
controller/northbridge, the memory, and the motherboard must all support
PC3200. If one of these is not, then your system will not run at PC3200
speeds. If they all support PC3200, then something is wrong if you cannot
run at PC3200 speeds.
>Is there a 333MHz version of the 3200+? I thought the 3200+ was just a
>400MHz FSB processor. I am always seeing adds in the paper saying that
>a computer that comes with an Athlon XP 3200+ with PC-2700 DDR memory...
>Now if it only comes in a 400MHz FSB version, isn't that ripping off the
>user because you'd almost have to drop the FSB to 333MHz unless the RAM
>was really, really good, right?
I suspect what's going on is that the system builder is saving some money
buy using the slower ram. But, at least they are telling you that they are
using the slower memory. I don't know what the XP3200+ FSB is rated at, so
I don't know if this is slower than the XP3200+ is capable of running.
(3200+ does not mean PC3200 memory speed.) Yes, you will have to run the
FSB at 166MHz for this memory to work "unless the RAM was really, really
good". You'd essentailly be overclocking the ram if you got it to work at
PC3200 speeds. Perhaps you could replace the ram with PC3200. Be careful if
you buy one of these systems. You may not be able to adjust the FSB speed
to even try to go PC3200. Many system builders limit what can be adjusted
in the BIOS and do not support overclocking by any means so you'd be stuck
with the speed they set. For example, I ahve an HP system and it cannot be
overclocked because the BIOS and the motherboard cannot be adjusted in any
way that would change to clocks seen by the memory or the cpu.