The Game Rundown: Finding CPU/GPU Bottlenecks, Part 1

Grand Theft Auto 4 EFLC, And Announcing Part 2

GTA 4 reacts so strongly to increases in graphics memory, CPU performance, and GPU performance that it's easy to constantly wonder if you're fully utilizing your expensive hardware or not. The game’s need for CPU speed is so strong that not even four cores can really satisfy it. Frame rates with a single-core CPU are so ridiculous that the game is practically unplayable. Even with two cores, GPU utilization is just 69 percent. Fewer than four cores are unthinkable for this game in our opinion.

Overclocking the CPU shows that the game just can't get enough CPU performance. To increase frame rates in GTA 4, you need at least four CPU cores, and when overclocking those cores to the max, you can start thinking about upgrading to a better graphics card. In the video settings, you can incrementally set the amount of graphics memory used by the game. This way, 768 MB can actually be enough, but as far as we could make out, only 630 MB are actually used at that setting. GTA 4 can take advantage of more than 1 GB of graphics memory, so if you like the game and play it a lot, you should definitely consider a graphics card with lots of onboard memory.

We did some further testing with a stronger AMD Radeon HD 5870, as well as two of them in a CrossFire setup. This test is meant to show you that despite the 100% CPU utilization, upgrading the graphics card still manages to further increase performance. We really like the idea of a game where the frame rates are actually increased--no matter what hardware upgrades you perform in order to improve performance. The GeForce GTX 460 is quite alright for GTA 4, but the AMD Radeon HD 5870 can handle a greater range of visual quality settings with its 1 GB of graphics memory.

In the second part of this story, we'll measure the hardware utilization in 10 more games. In addition, we'll assess overall performance, energy consumption, the effect of the CPU core count on game load times, and look at minimum frame rates before rendering our overall conclusion.

The games we'll include in Part 2 are: Just Cause 2, Kane & Lynch 2, Left 4 Dead 2, Mass Effect 2, Price of Persia: Forgotten Sands, S.T.A.L.K.E.R.: Call of Pripyat, StarCraft 2, Supreme Commander 2, and Wolfenstein.

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    Top Comments
  • experimentxx
    Best read for a pc gamer..
  • skora
    This needs to be a staple and have a section in the charts! This is by far one of the most useful articles I've read in a long time and really get down to what matters based on title. Great job TK!!!!!!!!!!!!

    Chris, make a section in the charts for this and keep them updated please!!!!!
  • karma831
    It was nice to see CPU and GPU load percentages.
  • Other Comments
  • adonn78
    Its True GTA4 can use 1.68GB of Video RAM at 1920x1200. And up to 1.8GB at higher res. The game can get pretty choppy unless you got a 2GB video card and a quad core. They even fixed the shadows so that they use less VRAM but it still craves GPU memory.
  • karma831
    It was nice to see CPU and GPU load percentages.
  • experimentxx
    Best read for a pc gamer..
  • Tamz_msc
    good article, cant wait for part 2!
  • Anonymous
    It would have nice to see what is making my favorite game Company Of Heroes be bottle-necked. I have a GTX 480 and an AMD 955@3.4 GHz and i still get laggy frame rates when there is heavy action and weather. Settings all maxed out on dx10 at 1400x900. I heard that the hard drive is what it makes it lag...
  • NuclearShadow
    GTA IV is one of the few games that I could actually see the performance difference with my own eyes when I was on my i7 920 rig with 6 GB of ram and a 4890 when I overclocked. That was a pretty damn good rig (and still is)

    Something I was amazed by in this article is that games like MW2 give pretty good frame rates when running on a single core. I would have never expected such. 59.1 fps would certainly be acceptable for game-play. Also its a shame to see that so many modern titles really don't take that much advantage having so many cores. It's been more than enough time for this to be adjusted and yet the performance difference in most titles seems minimal between 2 and 4 cores. (or in some cases even 1 core) At this rate everyone is going to commonly have 12 core CPU's and most games will still only truly utilize two.
  • baracubra
    OMG this is exactly the article I've been craving since my upgrade from 8800GT SLI to GTX 470.
    I have a Q6600 @ 3.6 but in BF:BC2 I only get around 40% GPU load and 80% CPU. However, my frame rates are in-line with those in this article...

    Anyway I really look forward to the next article!!!!
  • Anonymous
    Even though its an older game, i would really like to see crysis in part 2.
  • skora
    This needs to be a staple and have a section in the charts! This is by far one of the most useful articles I've read in a long time and really get down to what matters based on title. Great job TK!!!!!!!!!!!!

    Chris, make a section in the charts for this and keep them updated please!!!!!
  • archange
    You need a better GPU. With the GTX 460 768 MB, the bottleneck shifts strongly towards the GPU, making a comparison between dual/quad cores and 3 to 4 GHz quite pointless.

    This is best showcased by the introduction of the HD 5870 in single and crossfire mode - in the last chart - you can really see FPS picking up.
  • dEAne
    That's my card your talking. Thanks tom
  • Gamer-girl
    What about other screen resolutions?

    lower resolutions would be more cpu dependent wouldn't it?

    Is 1900x1200 the normal resolution now?
  • wribbs
    @skora totally agree +1
    However, this article is quite limited. Lets hope for some more comprehensive tests and results. I think a lot of what the results indicate is that PC graphics could be a lot better if developers could better utilize the hardware. Also it would be nice to see if AMD hardware mirrors the Intel+Nvidia results.
  • Qris
    Amazing read, just what I needed to know before buying a gaming PC, can't wait for part 2!
  • Simple11
    That was a good read indeed. Something people with a budget should read.
  • roversjoost
    This really shows to me that all the people that are saying game developers should start to use more cores are wrong. Clearly there is an abundance of CPU power. There simply isnt any need for more cores when the GPU cant keep up. While I love my quad core to make multitasking a much smoother experience, for gaming it is overkill.
  • punnar
    Great article, I have been waiting for something like this for a long time. Thank you Tom's!
  • Anonymous
    With such high resolution plus AA plus AF, it's quite clear that the graphics card is frequently the bottleneck. I think it would be interesting to have either a more powerful graphics card (5850 or 5870) and/or see the results without AA.
  • liquidsnake718
    Well lets see what the next gen CPUs with GPUs onboard can do and perhaps those GPUs can help xfire or sli with the attached GPU and act as a hybrid SLI or crossfire and speed things up.... interesting it it could will no?
  • nd22
    I think you should also consider Metro 2033, it's a great game and it's quite popular.