CPU clock speed and fsb confusion!!!

  Gandy 21:40 01 Jan 2005
Locked

I've just bought and blown up an AMD Athlon XP 3000+, fsb 333.
I seem to be getting terribly confused with the numbers.
I thought to get a speed of 3Ghz, with a multiplier of 15x, I would need a cpu clock of 200 Mhz, which successfully blew my processor.
Could some kind sole PLEASE explain to me the relationship between CPU speed, CPU clock speed and Front Side Bus speed?
I'm fed up of wasting money due to incorrect seating of the heat sink (x2) and latterly incorrect cpu clock setting.
I think I need to upgrade my HNC from "Thermionic Emission!!"

  howard60 21:42 01 Jan 2005

you have to go on the amd site and get the settings for your cpu model.

  CurlyWhirly 21:49 01 Jan 2005

I have the same CPU as you, namely, AMD Athlon XP 3000+ with a FSB of 167 mhz (333mhz DDR).
It actually runs as 2.17 Ghz and the multiplier is 13 so 13 x 167 = 2170 mhz.

  CurlyWhirly 21:52 01 Jan 2005

I thought to get a speed of 3Ghz, with a multiplier of 15x, I would need a cpu clock of 200 Mhz, which successfully blew my processor.


No wonder why the CPU blew as you had overclocked it by over 800 mhz!

  Gandy 22:01 01 Jan 2005

Thanks Howard60 and CurlyWhirly, another cpu on the way...will follow your guide CW, though still alittle confused with speed relationships!

  harps1h 22:01 01 Jan 2005

amd backed out of the race to higher clock speed a couple of years ago.

the rating they give are an equivelent speed setting that the cpu achieves by using a higher number of clock cycles.
this allows them to run more efficiently and in many cases are preferred as they are better to overclock.

therefore they rated your chip at 3000 as that is its equivelent speed factoring in the greater number of clock cycles it achieves.

there is a certain amount of overclocking you can do, but this is recommended to be done in stages as you will be able to decide what the most stable setting for your setting will.

in many caes if possible it is better to have a higher fsb coupled along with a slightly lower multiplier as this will increase the performance of your system. but be aware that you need to have adequate cooling for this to be successful. heat is your enemy as you have found out

  harps1h 22:03 01 Jan 2005

sorry typo. should read........the most stable setting for your system wiil be.

  CurlyWhirly 23:06 01 Jan 2005

though still alittle confused with speed relationships!


Your CPU runs 13 times faster than your motherboards FSB which runs at 166mhz.
However because your memory is DDR (Double Data Rate) it transmits TWICE the information per clock cycle i.e. 333mhz.
The reason WHY your CPU blew was when running at the stock speed of 2.17 Ghz it is the EQUIVALENT of a 3 Ghz processor (as harps1h rightly pointed out).
So when you unintentionally overclocked your CPU to 3 Ghz, you were probably running it at close to 4 Ghz in performance terms!
No wonder why it burned up! lol

  Gandy 10:00 03 Jan 2005

harps1h, thanks for that explanation of AMDs' philosophy on speed ratings, it helped clear the fog and confusion in my mind....pity I didn't know that beforehand!
Do you think I need to clear the cmos (to get rid of that 200Mhz clock setting) before I install my new cpu? Don't want to blow another chip!

  CurlyWhirly 10:20 03 Jan 2005

Do you think I need to clear the cmos (to get rid of that 200Mhz clock setting) before I install my new cpu? Don't want to blow another chip!


I don't claim to be an expert by any means, but I know for a fact that the 200Mhz clock setting is too high!
This is assuming that you intend on getting the SAME chip as a replacement i.e. AMD Athlon XP 3000+, fsb 333.
It should be set to 166Mhz.
As you say, clearing the CMOS should do it!
If left at 200mhz, when you turn your PC on (with the new processsor installed) it will run at 2.6Ghz i.e. 13 x 200 = 2600 which would still be TOO high in my opinion and would again probably fry your processor!
13 is the multiplier default.
Hope this helps!

  mrdsgs 11:24 03 Jan 2005

also check your motherboard

some have manual switches/jumpers to set fsb at 100/133/166 etc

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