I hear almost everywhere that CPU clock speed is not the only factor that defines the true speed of a CPU. Well. What are the other factors then? In which case a processor clocked at 1.6 Ghz is faster than one clocked at 2.0 Ghz?
Understanding Clock Speed and Other CPU Factors
cpu-speed
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The first thing, remember that Moore's Law isn't a law, it's just an observation. And it doesn't have to do with speed, not directly anyway.
Originally it was just an observation that component density pretty much doubles around every [time period], that's it, nothing to do with speed.
As a side effect, it effectively made things both faster (more things on the same chip, distances are closer) and cheaper (fewer chips needed, more chips per silicon wafer).
There are limits though. As chip design follows Moore's law and the components get smaller, new effects appear. As components get smaller, they get more surface area relative to their size, and the current leaks out, so it makes you need to pump more electricity into the chip. Eventually you lose enough juice that you make the chip hot and waste more current than you can use.
Though I'm not sure, this is probably the current speed limit, that the components are so small they're harder to make electronically stable. There's new materials to help this some, but until some wildly new material appears (diamonds, graphene) we're gonna get close to raw MHz speed limits.
That said, CPU MHz isn't computer speed, just like horsepower isn't speed for a car. There are a lot of ways to make things faster without a faster top MHz number.
LATE EDIT
Moore's law always referred to a process, that you can double density on chips at some regular repeating timeframe. Now it seems sub-20nm process may be stalled. New memory is being shipped on the same process as old memory. Yes, this is a single point, but it may be a harbinger of the future.
ANOTHER LATE EDIT An Ars Technica Article all but declaring it dead. Was fun having you around for 50 years.
Thanks everybody who tried to help me. Finally the problem was solved.
Other people reported that Current clock speed in BIOS is the same as Maximum clock speed. Which was different on my laptop - I had Current clock speed same as Minimum clock speed. There was something wrong with it not in OS, not in BIOS but "deeper".
- Current clock speed: 1.000 GHz
- Minimum clock speed: 1.000 GHz
- Maximum clock speed: 2.000 GHz
I also updated BIOS and nothing changed. When I set BIOS to default values and restarted, message was displayed saying
A 65W AC power adapter has been determined. Your system will operate slower and the battery may take more time to charge.
The adapter was already a suspect after about 7 hours of investigation, what might be the problem. This was the final evidence. What can cause CPU to operate slower? CPU speed can be set in BIOS, in OS, so something really deep in the system is the cause.
I use 65W car/air adapter all the time, it's small and great. I asked my friend to give me my old big 90W adapter back and.. The CPU works now at 2 GHz and is not throttled down.
Best Answer
Here are some of the things that can affect overall CPU speed:
The quoted CPU speed is the speed at which the internal clock runs. This is faster than the external clock (the FSB clock) which determines how fast the CPU can access the resources on the motherboard. A fast internal clock means the CPU can process faster, but a slower FSB means it takes longer to access memory and such.
This can be partially offset by the L1 cache (very fast memory inside the CPU itself) which can pre-fetch data from memory while the CPU is doing other things, so a larger L1 cache can yield a faster performance in certain circumstances.
The number of cores is important as well. A 1.6GHz dual core processor has approximately twice the processing speed (in optimal circumstances) of a single core 1.6GHz processor. This never realistically gets achieved in real life, but it is still much faster to have 2 cores than one. It's almost like having 2 processors.
The efficiency of the CPU itself has an effect too. Each instruction that the CPU performs takes a certain number of clock cycles to complete. A more efficient CPU will use less clock cycles to perform complex operations (floating point, for example) which makes the overall processing quicker.
The chipset on the motherboard can have an effect as well when it comes to the CPU accessing resources on the motherboard.
Pretty much everything in the computer has a bearing to a greater or lesser extent on the overall speed of the system.