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So, I am looking at building a new laptop.

Two examples of the processors I am looking at are:

  • Intel® Core™ i7-740QM Quad Core 1.73GHz 6MB
  • Intel® Core™ i5-520M Dual Core 2.40GHz 3MB

Now I realize that one has more cache that the other, but that is a significant difference in clock speed. If I take the cache out of it the equation, which is faster?

For example: If I am running a non-multithreaded app, is it going to run slower on the Quad core (1.73 GHz) than on the Dual Core (2.40Ghz)?

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Have you looked for any benchmarks? – ChrisF Oct 22 '10 at 16:34
woa building a laptop? you mean like barebones and up? – ioSamurai Oct 22 '10 at 18:59
@Shogun - No via Dell's website. You can pick CPUs, Memory and such. I guess "Building" is a bit misleading. I should have said, "selecting features" or something like that – Vaccano Oct 22 '10 at 20:08
up vote 8 down vote accepted

There is no one answer fits all.

If you are running a lot of other programs, the more cores the better. If not, having a higher base speed may be better.

As for raw benchmarks, The i7 740QM @ 1.73GHz is rated at 3634 Whilst the i5 520M @ 2.40GHzis rated at 2341

So, the I7 as you would expect is a higher performance processor. There are other factors such as FSB/DMI/cache to look at which can dramatically affect the speed of the processor.

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Where did you get those benchmark scores? Might be helpful for future related questions and those that don't know (i.e. me) – KronoS Oct 22 '10 at 19:36
@Kronos = - Love that site! Click on find and basically go through the big list! – William Hilsum Oct 22 '10 at 21:15

Unless you're into really crazy gaming.. I'd say speed doesn't really matter, and the quad core should do. Most things are multi-threaded these days, and you should be fine with the i7.

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If you are running 1 and only one application, and that application is single-threaded, and the operating system is not doing at least two things (e.g. printing and virus-scanning or defragmenting) and if the i7 core isn't faster for this particular application, it's possible that the dual-core CPU might be slightly faster, if this particular system at this particular moment is CPU-bound.

EDIT: As Shinrai points out, it's quite unlikely for all these things to be the case at the same time, and even if it's briefly true it won't stay true for long. In almost all real-world cases the quad-core CPU will give better performance.

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+1 if you edit it to clarify your subtext that all of these things being true simultaneously is very unlikely. :) – Shinrai Oct 22 '10 at 18:21

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