1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Clock rates (really need some help)

Discussion in 'A+' started by Juelz, Aug 24, 2015.

  1. Juelz

    Juelz Gigabyte Poster

    Top Poster
    of the Month

    1,176
    185
    176
    So I'm using the 801/802 exam cram and there is one section that has me stumped and I cant move on from, really hoping someone can help me work this out. I have tried to lay this out as clearly as I can. I'm a step away of emailing the author as I can't figure out where he got the 8 from... maybe @dmarsh can help me?

    Section: Internal clock speed:
    This is the internal frequency of the CPU and is the well-known number that CPUs are associated with. For the DP67DE motherboard I purchased the Intel Core i5-2400, which is rated at 3.1 GHz maximum. The CPU uses an internal multiplier based off the motherboard base clock. The multiplier for this particular CPU is 31. The math is as follows: base clock × multiplier = internal clock speed. In our example, that would be 100 MHz × 31 = 3.1 GHz.
    This motherboard can support faster and slower CPUs from a variety of groups, all the way from 1.6 GHz Celerons to 3.5 GHz Core I7-2700K CPUs. At 3.5 GHz, the default multiplier would be 35. My Tower PC motherboard, the DP35DP, uses the Intel Q8400 CPU that is rated at 2.66 GHz. The multiplier for this CPU is 8.(I'm ok up to this point! how can it be 8 wouldn't it be 26 as the processor is rated at 2.66? the 3.1 and 3.5GHz had corresponding multipliers e.g 31 and 35, so where has this random 8 come from?)So, 333 MHz × 8 = 2.66 GHz.
     
    Certifications: MTA Windows Fundamentals, ITIL Foundation, Mac Integration Basics 10.12
  2. dmarsh

    dmarsh Terabyte Poster

    3,782
    302
    184
    core speed × multiplier = cpu clock speed.

    Q8400 was LGA 775, which did support 333 MHz, DP35DP also had DDR2 677 memory.
    https://en.wikipedia.org/wiki/LGA_775
    http://ark.intel.com/products/50380/Intel-Desktop-Board-DP35DP

    So yes I'd say :- 333 MHz × 8 = 2.66 GHz.

    Core speed used to be sames as FSB speed, but then they started using separate multipliers for FSB and CPU freq.

    The system clock is generated by quartz crystal oscillator. Splitting a clock signal (or multiplying) is done by other circuits.
    http://www.tomshardware.co.uk/forum/338437-28-crystal-oscillator
    https://en.wikipedia.org/wiki/Crystal_oscillator
    https://en.wikipedia.org/wiki/Clock_generator
    https://en.wikipedia.org/wiki/Frequency_multiplier
     
    Last edited: Aug 24, 2015
    Certifications: CITP, BSc, HND, SCJP, SCJD, SCWCD, SCBCD, SCEA, N+, Sec+, Proj+, Server+, Linux+, MCTS, MCPD, MCSA, MCITP, CCDH
  3. Juelz

    Juelz Gigabyte Poster

    Top Poster
    of the Month

    1,176
    185
    176
    Thanks but how is the actual multiplier worked out? I understand everything else.
     
    Certifications: MTA Windows Fundamentals, ITIL Foundation, Mac Integration Basics 10.12
  4. dmarsh

    dmarsh Terabyte Poster

    3,782
    302
    184
    The BIOS has metadata about the CPU types supported and the chipset, it uses these to pick a 'clock multiplier', which then causes the chipset to essentially send signals to a frequency multiplier, to generate the correct clock rate. Its likely the frequency multiplier is also part of modern chipset.

    The CPU used to run at same speed as core in old computers, the was no multiplier, the CPU's got faster, the memory, cant run faster though, so we have effectively two clocks, the faster clock is generated by a 'multiplier' being applied to the slower clock.

    So we have multipliers. For every tick of the FSB clock, the CPU does x number of cycles.

    The CPU can execute so many instructions per cycle, (depends on the instructions and cache).
    The FSB can perform 1 or 2 memory accesses per clock, 2 for DDR.

    http://www.quartertothree.com/game-talk/archive/index.php?t-6544.html
     
    Last edited: Aug 25, 2015
    Certifications: CITP, BSc, HND, SCJP, SCJD, SCWCD, SCBCD, SCEA, N+, Sec+, Proj+, Server+, Linux+, MCTS, MCPD, MCSA, MCITP, CCDH
  5. Juelz

    Juelz Gigabyte Poster

    Top Poster
    of the Month

    1,176
    185
    176
    Thanks dmarsh
     
    Certifications: MTA Windows Fundamentals, ITIL Foundation, Mac Integration Basics 10.12
  6. thehappyone

    thehappyone New Member

    8
    3
    2
    lol I was fine till I got to this part too, "where the hell did he get the 8 from?!" "is it the 8 in Intel Q8400"

    Then I thought like you, 3.5Ghz is 3.5x10 giving me a multiplier of 35. Picked up the mike meyers book and it says core i7 3.4Ghz has a multiplier of 35. Now I'm even more confused. Im guessing you can only know the multiplier from product description.

    Atleast we can laugh at the irony of resorting to mike meyers book for a detailed explanation even though I left it because of all the fluff.
     
    Last edited: Dec 4, 2015

Share This Page

Loading...