UNDERclocking a XP cpu?

By autoshoes · 5 replies
Jun 17, 2002
  1. i was thinking of ugrading my system by just a little bit, and looking not to spend so much.

    right now i've got a duron 750, and my motherboard supports at max a 1.4ghz cpu at 200fsb. the motherboard does not do 266fsb :(

    looking at cpu prices, the 1.4ghz XP processor (1600+ @ ~$75) is cheaper than the 1.4 thunderbird 200fsb cpu (@ ~$100). heck, even the 1.4 266 tbird ($80) is cheaper than the 1.4 200

    now, i know the XP's run at 266fsb, but i was wondering what would happen if i were to underclock the XP cpu to 200fsb. would i be able to multiply up to 1.4ghz? if so would it be stable? or would i need to go to an xp with a compatable multiplyer to reach the speed?
    this is all assuming my motherboard supplied the right voltage, decent cooling, etc.

    i know i can get a lowerend XP cpu+motherboard+fan combo kit for something around $140, but i dont want to go to the hassle of installing a new mb, and possibly having to reinstall win2k + all my apps becasue of it.

    any suggestions on maxing out this motherboard would help.
  2. Didou

    Didou Bowtie extraordinair! Posts: 4,274

    First of all, you should see if there's a new BIOS available for your motherboard.

    In these situations, the best case scenario is the board won't recognise the CPU & post it as UNKNOWN CPU 1050 MHZ ( 100 * 10.5 for the 1600+ for example ).

    But as I said, that's best case scenario. A lot of KT133a boards don't support the AthlonXP at all, so it might be even harder to get it to work on a KT133 ( or AMD 750 ) board.
  3. autoshoes

    autoshoes TS Rookie Topic Starter

    my chipset


    • North Bridge VIA VT8363 (KT-133) system controller High Performance
    Athlon CPU Interface
    • South bridge VIA VT82C686A or VIA VT82C686B

    and there is no bios update to support XP's, i've already looked. it's said to not support any cpu with 266fsb (of course)

    oh, and i forgot to say, if i would be unlocking the cpu, would 200fsb x14 be possible?

    all in all, i'll probably end up just getting the 1.4 200fsb, but if there's another option, it'd be good to know.
  4. Didou

    Didou Bowtie extraordinair! Posts: 4,274

    I think your best bet would be the Athlon 1.4GHZ at 100FSB ( 200 ). You'll be having lots of trouble getting that AthlonXP to work & even if you do, running it at 100 FSB with SDRam won't let you really unlock its potential.

    If you get an Athlon 1.4GHZ with a 133FSB, you can unlock it & get 14*100 only if your motherboard support a 14x multiplier. Once again it's very important to know if your motherboard has the latest BIOS ( early boards had to be flashed because the max multiplier was 12.5 ).
  5. uncleel

    uncleel TS Rookie Posts: 980

    AMD-XP Motherboard Compatibility
    AMD-XP Motherboard Compatibility
  6. MrGaribaldi

    MrGaribaldi TechSpot Ambassador Posts: 2,512

    Re: my chipset

    Considering you've got the KT-133 chipsett, I'd say no, don't do it!

    Since the chipset is so old, you'll most likely end up with Didou's scenario (unknown cpu)...

    On a different note, yes you can set the cpu to 14x100... But you'd have to do it manually on the chip, by connecting the correct L1 bridges, which is much work... And chances are your system wouldn't be quite able to cope with it...

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