My CPU is Underclocked QUick Quesition

By dvduh ยท 13 replies
May 28, 2005
  1. My FSB is 100 Bus 200 according to CPU-z. My memory is running dual channel 133mhz. Its PC2100 rated ddr ram. When my computer starts up after unpluging the power supply it says no CPU Fan Detected even though i have one and it is running at like 2550 rpm. I have an Anthlon XP 2600 Thorobred B Rated at 333mhz but it is down clocked to 100mhz i wanted to know what i should check before i clock it up to 266mhz to make it equal with the RAM.


    my cpu id number is AXDA2600D KV3d
  2. MrGaribaldi

    MrGaribaldi TechSpot Ambassador Posts: 2,512

    First off, don't oc the system to 266Mhz... You only need to set the FSB to 166, and your cpu will run at correct speeds. Your ram should be running at 133Mhz. When you then take into account the DDR, you get the ram running at 266"Mhz" effectively.
  3. dvduh

    dvduh TS Rookie Topic Starter

    if i up the clock to 166 on the processor wont that raisde my ram's clock to 166 as well? also according to AMD it should be clocked at 333mhz so why wouldn't i up it that high? or is 333 the BUS and not the FSB
  4. Didou

    Didou Bowtie extraordinair! Posts: 4,274

    The Athlon FSB is DDR (dual-data rate) just like DDR Ram. It allows to have a better efficiency then SDR Ram (single-data rate) by using the same frequency (133mhz for example) but using both the rising & the lowering part of each clock to carry out its operations.

    So physicaly, you set the Ram & the CPU FSB to 133mhz & they will work internaly at 266. In your case, a 333mhz Athlon FSB means it works at 166mhz so you can set your FSB to that. Which brings us to the next problem.

    The Ram should be PC2700 for such a CPU. PC2100 is too slow & will either fail because it cannot run at PC2700 speeds or your motherboard can let your run the FSb & the memory at different speeds (asynchronous operations) but then you will be limiting the performance of your CPU.
  5. dvduh

    dvduh TS Rookie Topic Starter

    why did my motherboard underclaock it?

    would it be beecause it thinks i dont have a fan?
  6. Samstoned

    Samstoned TechSpot Paladin Posts: 1,018

    where these the defaults on startup?
    best thing is reset defaults to optimum settings
    then change the automatic sfd to start at 133 and work your way up till you loose the video on boot
    reset the cmos and set the speed to just before you lost vid
    I have my amd setup over clocked at 284
    not much but no heatspreader just standard ddr shell nio fan gets warm thats all.check around in bios there are 2 settings that need changed
    I have not had much time to play with this rig. seems to boot fast
    only 1 freeze so far .
    your MB manufacturer should have a guide for changes to bios
  7. dvduh

    dvduh TS Rookie Topic Starter

    you say there are two setting that need to be changed. WHat are they though : P

    also there was this program tha simulated a full processor load so you could test you temperratures but i forget its name does anyone know it or anyhting similar
  8. AtK SpAdE

    AtK SpAdE TechSpot Chancellor Posts: 1,495

    To test your CPU at full load, there is a program called CPU-Burn-in. I use it all the time to check stability when i OC. As far as how the multiplier got set down, it happens once and awhile uses a porblem with the CMOS battery. If i happens alot, then i would be concerned, but BIOS has its occasional hiccups.

  9. dvduh

    dvduh TS Rookie Topic Starter

    yeah i did change my cmos battery once now that i think of it. How do i know the correct multiplier to be running for my cpu?
  10. Didou

    Didou Bowtie extraordinair! Posts: 4,274

    You cannot change the multiplier, it's locked. Simply set the FSB to 166mhz to have your CPU run at the proper speed.
  11. dvduh

    dvduh TS Rookie Topic Starter

    thats what i did. But my bios lets me change the multiplier voltage and all that jazz
  12. Didou

    Didou Bowtie extraordinair! Posts: 4,274

    It's locked, changing it won't do anything.
  13. MrGaribaldi

    MrGaribaldi TechSpot Ambassador Posts: 2,512

    You only need to worry about setting the correct FSB... Voltage & al isn't interesting when you're running at stock speeds... If you were going to overclock like AtK_SpAdE say, then you'd be messing around with those too..

    But for noe I suggest sticking to trying to get it to work at stock speeds...
  14. Charles Hammond

    Charles Hammond TS Rookie Posts: 59

    If your MB tells you you have no fan then that usually indicates you dont have a fan plugged into the 3 prong fan plug on the motherboard for the device that is indicated.

    Some motherboards will not post if you do not plug a 3 pronged fan plug into the motherboard in the correct location for the CPU. Additionally some motherboards may also look for an exhaust fan.
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