How can it be..

Discussion in 'iMac' started by MacApple21, Oct 19, 2009.

  1. MacApple21 macrumors member


    Mar 12, 2009
    That the clock speeds on the new mobile Nehalem CPU are lower than on the older, bigger (manufacturing process), supposedly hotter running micro architecture Core 2?
    We have mobile Core 2 quads running at 2,53 Ghz and 45 W (QX9300), why can't Intel make the mobile Nehalems run at similar speeds :confused:
  2. dwd3885 macrumors 68020

    Dec 10, 2004
    Remember Pentium 4 or even G5? Clock speed is irrelevant from arcitecture to architecture. A 2 GHz Core 2 Duo will run faster than a 3 GHz Pentium 4.

    Also, the Nehalem's overclock. So a 1.73 Nehalem will go to something like 2.8 on dual core and 3.06 on single core.
  3. MacApple21 thread starter macrumors member


    Mar 12, 2009
    Yeah but..

    Still why does the clock speed decrease, why not just keep it at a certain level, is it physical limitations or what. In any case a 2,5 ghz i7 is faster (better) than a 2 ghz i7, turbo boost aside. I just don't understand the reason(s) why they have to decrease the clock speeds at every architecture upgrade.
    I'm just curios :confused:
  4. mZex macrumors member


    Aug 9, 2009

    Computer performance is often described in terms of clock speed (usually in MHz or GHz). This refers to the cycles per second of the main clock of the CPU. However, this metric is somewhat misleading, as a machine with a higher clock rate may not necessarily have higher performance. As a result manufacturers have moved away from clock speed as a measure of performance.

    Computer performance can also be measured with the amount of cache a processor has. If the speed, MHz or GHz, were to be a car then the cache is like the gas tank. No matter how fast the car goes, it will still need to get gas. The higher the speed, and the greater the cache, the faster a processor runs.

    Modern CPUs can execute multiple instructions per clock cycle, which dramatically speeds up a program. Other factors influence speed, such as the mix of functional units, bus speeds, available memory, and the type and order of instructions in the programs being run.

    There are two main types of speed, latency and throughput. Latency is the time between the start of a process and its completion. Throughput is the amount of work done per unit time. Interrupt latency is the guaranteed maximum response time of the system to an electronic event (e.g. when the disk drive finishes moving some data).

    Performance is affected by a very wide range of design choices — for example, pipelining a processor usually makes latency worse (slower) but makes throughput better. Computers that control machinery usually need low interrupt latencies. These computers operate in a real-time environment and fail if an operation is not completed in a specified amount of time. For example, computer-controlled anti-lock brakes must begin braking almost immediately after they have been instructed to brake.

    The performance of a computer can be measured using other metrics, depending upon its application domain. A system may be CPU bound (as in numerical calculation), I/O bound (as in a webserving application) or memory bound (as in video editing). Power consumption has become important in servers and portable devices like laptops.

    Benchmarking tries to take all these factors into account by measuring the time a computer takes to run through a series of test programs. Although benchmarking shows strengths, it may not help one to choose a computer. Often the measured machines split on different measures. For example, one system might handle scientific applications quickly, while another might play popular video games more smoothly. Furthermore, designers have been known to add special features to their products, whether in hardware or software, which permit a specific benchmark to execute quickly but which do not offer similar advantages to other, more general tasks.

    Says wikipedia :p

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