AMD Athlon processor changed speed by itself.

  RLB 09:19 11 Feb 2009

Hi, I am a bit baffled by this one. My PSU went pop at the weekend and after fitting a new one I had some issues with the display not working. I stripped the pc down to check over thoroughly. On finding nothing broken or displaced I rebuilt it and hey presto all was working again. Apart from one slight difference. When booting up I noticed that my processor has changed itself from an AMD Athlon XP 2800MHz to a 1263MHz. The system itself does not seem any slower other than when shutting down. Anyone have any ideas? I have checked speed with CPU-Z and it says the same.

  MAJ 10:18 11 Feb 2009

Do you mean your processor is an AMD Athlon XP 2800+? AMD don't name their processors by clock speed, so it wouldn't be an AMD Athlon XP 2800MHz. The AMD Athlon XP 2800+ runs at a clock speed of 2083MHz with an FSB of 166MHz and a Multiplier of 12.5 (which is usually fixed). If your processor is an AMD Athlon XP 2800+ then it's possible the FSB has slipped to 100MHz in the BIOS, giving a clock speed of 1250MHz, close to your present stated speed of 1263MHz.

  Stuartli 10:41 11 Feb 2009

MAJ's reasoning is correct.

You should change the FSB in the Bios to 200MHz - it's likely that the Default Bios settings have been activated.

Don't worry, it happens to others, including me..:-)

I had to temporarily use the Default Bios settings about a year ago and discovered after establishing the Status Quo that my Athlon XP 3200+ had become a 1.1MHz rather than 2.2MHz, as the FSB had defaulted to 100MHz.

Upping the FSB to 200MHz again was sufficient.

  MAJ 10:46 11 Feb 2009

If it is an AMD Athlon XP 2800+ (we're not sure yet), then the FSB should be set to 166MHz rather than 200MHz.

  MAJ 10:53 11 Feb 2009

The AMD Athlon XP 2800+ has a choice of two different cores, The "Barton" core running at a clock speed of 2083MHz and the "Thoroughbred-B" core running at a clock speed of 2250MHz. The former has a Multiplier of 12.5 while the latter has a Multiplier of 13.5, but both use an FSB of 166MHz.

  RLB 10:57 11 Feb 2009

Sorry for the mistake. It is an XP 2800+ with a barton core. So shall I set it to 166MHz or 200MHz? Will it perform better at 200?

  MAJ 10:58 11 Feb 2009

Set it to 166MHz.

  RLB 11:08 11 Feb 2009

Thanks MAJ you are a star. This has rectified the problem. CPU-Z is displaying 2800+ and core speed of 2087MHz, multiplier 12.5, bus speed 167MHz, rated FSB 334MHz. Thanks again for the fast response.

  MAJ 11:23 11 Feb 2009

Happy to help, RLB, glad it's back to normal for you.

  Stuartli 13:08 11 Feb 2009

Apologies for the slightly higher FSB figure - I only had mine in mind at the time...:-)

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