What is the difference between

  • 2.7GHz Quad-core Intel Core i7 and
  • 2.8GHz Quad-core Intel Core i7

I know the difference is 0.1 GHz, but what does that mean?
It seems quite something, cause it costs $250.

Can anyone explain what it means or where to find it?
I know you can't give me a simple answer, so I would like to learn about it.
I want to understand what it means and how it affects the performance of the computer.
Where do I start?

I'm gonna use my computer for programming and video-editing, but probably not at the same time.

  • 1
    Which two computers have those processors? Putting the same V8 engine in a Ford Taurus will drive differently than if you put it in a Corvette.
    – bmike
    Aug 27, 2013 at 12:48

4 Answers 4


I assume you're asking about the Macbook Pro retina, since that's the one that offers a choice between 2.7 or 2.8GHz CPUs right now. Apple doesn't like to give the actual CPU model designations, but Google can help us here, and we learn that the two CPUs are the i7-3740QM and i7-3840QM. Googling again for the difference (http://lmgtfy.com/?q=i7-3840QM+vs+i7-3740QM) finds that in addition to clock rate, there are differences in cache sizes. But within the first page of hits on that search, you can see benchmarks that show nearly identical performance for the workloads tested.

In short, I wouldn't spend $250 more for that CPU. (But I wouldn't buy a retina MBp either. :)


Very basically, this value designates the speed at which your computer's CPU runs. The faster the CPU speed, the faster, in general, the computer can process data.

In practical terms, the amount of memory, and the presence of a solid-state drive vs. a traditional HDD will make more difference in the performance of your computer than will a .1 GHz difference in clock speed.

  • All the other specifications are the same, the difference is just the .1Ghz.
    – user55903
    Aug 27, 2013 at 12:35
  • Well, of the criteria listed above, the clock speed, especially one that is such a small difference, will mean the least. Personally, I would not pay $250 for a .1 GHz bump, but others may have a differing view.
    – Dave
    Aug 27, 2013 at 12:40

There are multiple factors on which the clock speed depends such as the number of cores, cache memory, architecture etc.Clock speed is the rate at which a processor executes a task and is measured in Hertz, Megahertz or Gigahertz (GHz). One cycle per second is called as “Hertz”. Gigahertz (GHz) means 1 billion cycles per second and when you talk about 2.4 GHz processor, you usually mean that this is the maximum frequency of the clock to each core which is 2.4 billion cycles per second. But if one CPU is dual core having 2.6ghz of speed and another one is a quad core having 2.5 GHz speed then obviously the second one will be faster because each core is going to have a speed of 2.5 GHz which means 4 cores * 2.5GHz.

Reference: What does GHz in processor speed mean?Clock Speed of Processor


I won't begin to guess what you might spend the $250 on if you didn't get that CPU bump, but most people should buy everything else they need (AppleCare, cables, software, cases) before paying to upgrade the CPU when there isn't a documented need to make money on a known task that would save time due to increased CPU speed.

The larger question is how to map Apple's CPU to Intel and whether industry benchmarks that will show a faster CPU does more math actually translates into an observable effect for the average (or for a specific) user.

I would say you could get good advice from the following resources:

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