Part 2: How Many CPU Cores Do You Need?

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Multitasking Benchmarks

This is the new test we've added to see just how much multiple CPU cores can help when running more than one application. We'll be testing the same World in Conflict benchmark seen on the previous page, but this time we'll run the AVG antivirus scanner in the background. This is something that probably happens to a lot of folks on a daily basis.

Let's have a look at the results:

This is why I schedule my virus scans to run at 4:00 AM in the morning, folks. And it also demonstrates why someone who isn't a power user might still want to consider a CPU with more than three cores.

Nothing illustrates this better than the difference between the quad- and triple-core results. Without an application running in the background, they both pull nearly-identical frame rates. However, when AVG is running a virus scan, the triple-core CPU takes a massive hit, with frame rates as low as 34 FPS compared to the quad-core's 82 FPS.

While the minimum numbers don't look too terribly bad as far as playability goes, the effect was definitely pronounced in the game benchmark where obvious stutters could be seen as we utilized fewer and fewer CPU cores.

One interesting result is that, when multiple applications are running, the single-core CPU achieved a similar result compared to the dual-core CPU. Presumably, with a single-core CPU, the operating system is prioritizing the application that has focus and allocates a smaller percentage of CPU cycles to the background application.

In any case, there are two lessons to be learned here: first, try to avoid a virus scan during your gaming sessions. Second, multiple CPU cores definitely offer a marked performance advantage if you're a heavy multitasker--an increasingly prevalent usage model in today's world of getting more done in less time. Whether virus scanning, media encoding, or downloading from the Internet, more CPU cores are a good idea.

Don Woligroski
77 Comments Comment from the forums
  • erdinger
    Very intresting article,now I'm even happyery I bought a Phenom II 720 for my gaming rig!
    Reply
  • icepick314
    "In any case, there are two lessons to be learned here: first, try to avoid a virus scan during your gaming sessions."

    what kind of PC gamer does virus scanning while running a game?
    Reply
  • KyleSTL
    Why no power consumption testing? I was a little curious what disabling cores in the OS would do to power consumption under load. A little let down, but otherwise good article. It's good to see a scaling article at least yearly since people refer to the dual/quad debate so often and often the tests that were run within article that are referenced are out of date and irrelavent.
    Reply
  • Onus
    Good article, and very interesting.
    Now I really hope I can unlock the 4th core when my 720BE arrives (hopefully later this afternoon), but I won't sweat it.
    Did you happen to test if it made a difference what scan priority was set in AVG? I'd really like to see those numbers.
    Reply
  • So, how did you manage to get an Nvidia-based graphics card (Gigabyte GV-N250ZL-1GI 1 GB DDR3 PCIe) up and running with the ATI Catalyst 9.6 drivers?! ;-)

    Besides that bit of confusion, thanks for the benchmarks!
    Reply
  • 1word
    very happy with my 720 BE. I constantly check with the activity on the cores, and many many apps use all three cores, or multi- tasking uses all the 3 cores. some activities like defrag uses only 2 cores. image editing software, and general applications like browsers, office apps use all three cores, especially when multi tasking.

    i'm very happy with the AMD 720BE.
    Reply
  • jcknouse
    KyleSTLWhy no power consumption testing? I was a little curious what disabling cores in the OS would do to power consumption under load. A little let down, but otherwise good article. It's good to see a scaling article at least yearly since people refer to the dual/quad debate so often and often the tests that were run within article that are referenced are out of date and irrelavent.
    I liked the article well, but I was too finding myself asking "What was more power efficient? the PII x2 550 BE or the PII x2 955 BE?

    Would love to know, even if it was just that you guys just happened to glance at a P3 Kill-a-watt or some other meter you had inline during testing or something.

    Thanks for great work, guys :)
    Reply
  • erichlund
    It's true that an application like iTunes does not benefit from multiple cores, when run without any other apps. However, it also doesn't compete for more than one core when multiple apps are running, so single threaded apps also benefit from multiple cores when users are multi-tasking.

    What one really needs to know with iTunes and it's competing applications is: Which one competes most efficiently in a multi-processing environment? In other words, which uses the least resources while performing essential tasks, leaving the most resources for the other tasks being performed? To say it in perhaps the clearest way, what applications play well with other types while multi-tasking, and which hog resources, making it more difficult to multi-task?

    That's not really the point of this test, but it may lead to some interesting future evaluations.
    Reply
  • Onus
    ^Yes, that's why it would be interesting to see if (and how much) the impact varied if AVG was set to slow, normal, or fast for its scan priority.
    Reply
  • paranoidmage
    You shouldn't test the games at 1024x786 at low details. These benchmarks are supposed to simulate actual usage. No one will actually run games at that resolution and detail unless their computer is a dinosaur. If you want to remove bottlenecks, use a better GPU like a 4890.

    How do I know if multiple core will actually help me? I run games at 1920x1200 with med-high details.
    Reply