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Thunderbird and fsb

 
 
Brook
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      04-07-2004, 03:32 PM
I've got an early socket a Athlon that uses 100 MHz front side bus. I
read somewhere that the Thunderbird becomes unstable beyond 150MHz fsb.
Is this true? I thought cpus didn't care much about the external memory
speed. I think my motherboard is stuffed and would be happy to get a new
motherboard with 200 MHz fsb and 5x multiplier. Thanks

 
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Jim
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      04-11-2004, 05:33 AM
Ok, you got all the buzz words, just not arranged correctly

The FSB is a function of the CPU, not memory or motherboard. Your older
Athlon CPU *is* a 100MHz FSB. This FSB is then multipled by the multipler
(works out nice, eh?) to give you the CPU speed. So if the multipler is
say, 13, that's 13 x 100MHz = 1300MHz = 1.3GHz processor.

Ideally, you want to keep the CPU FSB and memory freq "in sync". So a CPU
FSB of 100MHz is best paired w/ 100MHz RAM. In this case, that would be
PC1600 (100MHz x 2 (for DDR) x 8 (bits wide) = 1600). PC1600, hmm...,
that's pretty old stuff! They haven't made that in a looooong time. For
all intents and purposes, your CPU and (if you have PC1600) memory have hit
the end of the road. I doubt you'll even find any new motherboard w/ a
starting point of less than 133MHz for either CPU FSB or memory (PC2100).

So dump the old stuff on eBay, shop around for a nice 200MHz motherboard,
and have at it.

HTH

Jim


"Brook" <(E-Mail Removed)> wrote in message news:(E-Mail Removed)...
> I've got an early socket a Athlon that uses 100 MHz front side bus. I
> read somewhere that the Thunderbird becomes unstable beyond 150MHz fsb.
> Is this true? I thought cpus didn't care much about the external memory
> speed. I think my motherboard is stuffed and would be happy to get a new
> motherboard with 200 MHz fsb and 5x multiplier. Thanks
>



 
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Wes Newell
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      04-11-2004, 08:50 AM
On Sat, 10 Apr 2004 22:33:17 -0700, Jim wrote:

> Ok, you got all the buzz words, just not arranged correctly
>
> The FSB is a function of the CPU, not memory or motherboard.


I'm afraid you're mistaken. The FSB clock is generated by the MB, not the
cpu. The cpu uses this clock to determine the speed the cpu runs at also.
The FSB connects to the system northbridge and all data passes through it
DDR. You are correct about the memory though, and anything else. The FSB
connects only between the cpu and the northbridge. Anything destined for
the cpu passes through it.

> Your older Athlon CPU *is* a 100MHz FSB. This FSB is then multipled by the
> multipler (works out nice, eh?) to give you the CPU speed. So if the
> multipler is say, 13, that's 13 x 100MHz = 1300MHz = 1.3GHz processor.
>

It's only a 100Mhz FSB in the sense that is what you should run it at
to obtain the rated speed of the cpu. You can run it anywhere you want, as
long as the cpu multiplier doesn't try to run the cpu faster than it's
capable of. I've run mine at anywhere from 70-215MHz.

> Ideally, you want to keep the CPU FSB and memory freq "in sync". So a
> CPU FSB of 100MHz is best paired w/ 100MHz RAM. In this case, that
> would be PC1600 (100MHz x 2 (for DDR) x 8 (bits wide) = 1600). PC1600,
> hmm..., that's pretty old stuff! They haven't made that in a looooong
> time. For all intents and purposes, your CPU and (if you have PC1600)
> memory have hit the end of the road. I doubt you'll even find any new
> motherboard w/ a starting point of less than 133MHz for either CPU FSB
> or memory (PC2100).
>

With DDR ram it's true you want to run in sync, but with older sdram (non
DDR), it best to run it faster than the FSB if possible, since the FSB is
DDR, and the ram bus isn't.

> So dump the old stuff on eBay, shop around for a nice 200MHz
> motherboard, and have at it.
>

There's really not a whole lot to gain. I can't tell the difference
between running my cpu at 24x100 or or 12x200. Well maybe a little, but
not as much as I would have thought. I calculated about 3% increase in
performance for every 33MHz you go up in FSB speed, in real life apps, not
benchmarks which can be very deceiving.

> "Brook" <(E-Mail Removed)> wrote in message
> news:(E-Mail Removed)...
>> I've got an early socket a Athlon that uses 100 MHz front side bus. I
>> read somewhere that the Thunderbird becomes unstable beyond 150MHz fsb.
>> Is this true? I thought cpus didn't care much about the external memory
>> speed. I think my motherboard is stuffed and would be happy to get a
>> new motherboard with 200 MHz fsb and 5x multiplier. Thanks
>>

Don't waste your time and money just changing the MB. You won't notice
much difference. If you have to go in stages, replace the CPU first. A
2000MHz Tbred B core or barton will do wonders for that old board. Just
make sure it's not a newer internally multiplier locked one.

--
Abit KT7-Raid (KT133) Tbred B core CPU @2400MHz (24x100FSB)
http://mysite.verizon.net/res0exft/cpu.htm
 
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