Part 2: How Many CPU Cores Do You Need?

Performance Analysis

Let's begin by looking at the big picture. Here is a graph showing the average relative performance when using the Phenom II with one, two, three, and four CPU cores enabled:

The blue bar represents game performance, the green bar represents application performance, and the dark bar represents synthetic performance.

First off, let's look at the gaming results. We get the impression that, compared to a single-core CPU, there is a huge benefit to using at least a dual-core CPU when gaming. After that, increasing the number of CPU cores provides a small increase in performance, with triple-core CPUs providing the same performance as a quad-core processor.

When we scrutinize application performance, we see a more linear progression, suggesting that multithreaded apps are better-suited to take advantage of multiple CPU cores. Do keep in mind that certain applications showed no increase in performance, as they aren't threaded. So, the programs you run will directly influence the actual performance increase.

The synthetic results appear as slightly exaggerated application results, which bodes well for the argument that synthetic benchmarks are a useful tool in looking forward--here, measuring multithreaded performance.

It is interesting to note that once four CPU cores are used, both application and game performance run about twice as fast as they do on a single-core CPU.

Now that we've examined this, let's look at the average performance graph from the previous article, where we used the Core 2 Quad Q6600 as our test case:

In general, the results paint a similar picture, even though some of the details are a little different. The most notable change from the Phenom II results is the synthetic results, which seem far too optimistic in the Core 2 Quad tests. Application performance is similar on the whole, showing comparable increases with each CPU core that is utilized. Even the game results are fairly close. Therefore, we can say with some certainty that the split cache on the Core 2 Quad Q6600 didn't affect the results enough to invalidate them in the previous review.

The other notable tidbit we learned wasn't too much of a surprise: as the concurrent application benchmark demonstrated, even though triple- and quad-core CPUs might show nearly-identical results in a given benchmark, these results can drastically change when more than one application is run at the same time. If you have a quad-core CPU, you're more likely to be able to run an application in the background without as much of a performance penalty. Conversely, folks with fewer CPU cores at their disposal may want to pay attention to the apps running in the background and terminate them if they're participating in a CPU-intensive task, like a game.

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  • redkachina
    great..I was waiting for this one..
  • the Innocent
    This why I went with the Q6600 I do more than one thing at a time.
  • BrightCandle
    I am so glad you finally did this test. With dual cores having an advantage of 25% clock speed its actually now apparent that for gamers dual cores are the better option - cheaper and faster.
  • avatar_raq
    Putting core i7 aside, those charts show that dual cores are the most attractive for gaming,plus they tend to have lower prices and higher clocks than quads, add better and easier overclockability on top of that, not to say lower power consumption (in general), and the choice seems no brainer, for all but the most spoiled gamer!
    Nice article..
  • papalarge123
    i dont believe that the dual cores are the way to go/best choice for gaming, as software from this point on will be callibrated for quads or above,

    it clearly shows an improvement from dual to triple or even quads, and if most people are like myself when it comes to computing and gaming, pulling the best out of the system from the budget available, then the triple and quad core cpu's sure look better than the dual cores.

    also down to price and overclocking ability, then the quads from intel can reach virtually the same speeds as the duals and with only a small price difference, making a better price to performance gain overall.
  • goozaymunanos
    why are they only showing gaming benchmarks at 1024x768?

    i'm a bit behind the curve and even i'm playing at 1680x1050?


    p.s. stuff and nonsense:
  • chispa
    @goozaymunanos I think it's because the higher resolutions stress mainly the video card, while this test was to highlight the differences in the processors. Thus the video card was stressed as little as possible to allow the processor differences to shine through.
  • lekiamiga
    but that makes the game benchmarks basically synthetic as gamers wont be running at those low resolutions and low gfx levels on new hardware.

    They should do gaming benchmarks at high deatails so i know how much of a difference a quad cpu will really make on the games.
  • Anonymous
    Nice, I already ordered 955 :) Can't wait for it.
  • Anonymous
    Am I the only one quite disappointed with the results? :(
    I expected far better performance from dual / quad cores than a single core - basically like running multiple processors.

    So I was expecting twice the performance with dual cores, and 4-times the performance with 4 cores.
    I guess this might be expected where the processors were using dedicated caches?

    Perhaps it also reveals that Windows isn't correctly taking advantage of the power of 2-4 cores - i.e. the kernel isn't too intelligently dividing multi-threaded / multi-apps capability to multiple cores.
  • Anonymous
    I thought the question was mostly "Which applications really benefit from more than 2 cores?" anyway?

    Would be interesting to see a benchmark with Supreme Commander since that's meant to be a well threaded game, and really needs CPU performance when a large number of units are in the game.

    Another application which can really use multiple cores is software compilation (e.g. try compiling a kernel with the option: -j 4). But since the compiler itself is not (normally) threaded, but just run several times in parallel, clearly the performance increase is linear.
  • Anonymous
    I suspect differences may be even more apparent on a Linux system than with a MSoft OS. Generally, Linux kernels multi-task more transparently amd should lend themselves to multi-threaded multi-processor tasking more efficently.
  • wild9
    avatar_raqPutting core i7 aside, those charts show that dual cores are the most attractive for gaming,plus they tend to have lower prices and higher clocks than quads, add better and easier overclockability on top of that, not to say lower power consumption (in general), and the choice seems no brainer, for all but the most spoiled gamer!Nice article..

    That's why the socket AM3-based Athlon II/Phenom II x2 seem so appealing, considering their cost. Not saying Core 2 is bad, either, just that I have some Socket AM2 stuff lying around and for a relatively cheap price these deliver killer blows for games, as well as provide a very good overclocking potential. Most of my clients have AMD's due to price restrictions but I have no complaints and at least I know that when I install these parts they're gonna run cool and fast.
  • tygrus
    And what happens when data intensive tasks run out of RAM or disk I/O. We need faster storage.
    We still need faster fingers and eyes to go with the faster computers.