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Will my CPU bottleneck a GeForce GTX 285?

  1. Sep 19, 2009 #1
    Because my current graphics card runs burning-hot (past 100 *C) under load, I was hoping of getting a better, and hopefully cooler-running graphics card for Christmas. The overclocking features on my motherboard have been permanently disabled by the manufacturer (Gateway) making any kind of overclock to solve any bottleneck impossible. Will my C2Q Q9400 running on it's stock 2.66 GHz bottleneck a single GeForce GTX 285? Is a Corsair TX 750 (750W) PSU enough to power it? My motherboard only has a single PCIe 2.0 x16 slot, making SLI physically impossible. Approximately how much faster is a GTX 285 than a Radeon HD 4850?

    Personally, I would wait for the next-generation DX11 cards to come out, but without any ability to overclock, or buy a new processor without voiding the warranty, I would be left with a terrible bottleneck and probably lesser performance than with my current GPU. The new Core i9 processors are probably the only CPU's capable of correctly running the GeForce GTX 300 and Radeon HD 5000 series cards.

    Is there any way of telling if I have a CPU/GPU bottleneck?
     
  2. jcsd
  3. Sep 19, 2009 #2
    The main way you can tell if you have a CPU or GPU bottleneck is to watch your frame rates while running various resolutions. As far as being able to predict where a bottleneck will be within a system, it's all just an educated guess unless you can actually try different configurations. Either way, there will always be a bottleneck of some sort present.

    Beyond a shadow of a doubt though, you'll see an improvement in performance if you stepped up to a 285 GTX from a 4850. Exactly How much of an improvement you'll see will depend on the resolutions you plan on running. A 285 GTX will crank out ~50% more fps at resolutions over well 1920x1080, but the increase in frame rates will down as you approach lower resolutions (ie; 1680x1050 and down). Possibly dipping down to only a difference of ~10 to 20%.

    If you have a fairly efficient power supply, all you'll need is a 550W. In my primary gaming computer I'm running an overclocked 285 GTX along with an i7 920 overclocked to 4GHz. When loading the processor and graphics card to 100% with SETI@home my power draw goes up to ~450W. 750W is plenty.

    If I may make a suggestion, hold off on buying a 285 GTX and get a better motherboard. You'll see a much greater increase in performance (at half the cost) if you were able to overclock your processor while keeping it sufficiently cool. IMO, for gaming, you still have an excellent processor with potential.
     
  4. Sep 20, 2009 #3
    How can I overclock my processor without constantly causing my computer to crash, become unstable, not start, etc? How do I determine which voltage is appropriate for my desired clock? My CPU at it's current stock clock speeds runs at about 30* Celsius idle with it's stock cooler. Under load, I have no idea. How high do you think I would be able to get it up to with a Coolermaster V8? 3.5?

    My current PC case has very poor airflow. Switching out the case to a larger, and cooler-running one would void the warranty according to the store I bought it from.
     
  5. Sep 20, 2009 #4
    The way you figure out the highest stable overclock is to just slowly increase the FSB, then run a quick program that will load the processor 100% and watch for stability issues. The only time you need to increase the CPU voltage is when it truly needs it for stability. Wen you notice a program or game crashing to the desktop, up the voltage just a bit. Say, .05 volts. If you up it and it keeps the program from crashing, you now know that your pushing the voltage limitations, which is a good thing. It's one less factor that's unknown and gives you something to play with. IF you up the voltage a bit an it makes no difference stability-wise, the problem is somewhere else (memory configuration, heat, ect).

    For example, when I first started overclocking this i7, I didn't have to make a single voltage adjustment till I reached 3.5GHz. Even at 4GHz I still don't have it that much higher than recommended (still within Intel spec voltages).

    Honestly, don't mess with the Coolermaster V8. It's more hype than anything else. A couple of the best coolers you can get are the Zalman CNPS9500, Xigmatek Dark Knight-S1283V, Thermalright Ultra-120, or the Noctua NH-U12P. I'm currently using the NH-U12P in my primary computer. Temps at idle are; CPU: 33*C and MB: 32*C. When fully loaded the temps climb to; CPU: 62*C and MB: 35*C.

    You should be able to 3.5GHz if the temps stay low enough.
     
  6. Sep 21, 2009 #5
    Approximately how much faster is a GTX 285 than an HD 4850?
     
  7. Sep 21, 2009 #6
    Like I said, it depends on the resolution you plan to run it at. It won't really start to shine until you reach higher resolutions.

    What size monitor do you have and what resolutions do you plan to run?
     
  8. Sep 21, 2009 #7
    To give you an idea of what i'm talking about, check out this iXBT Labs shootout between Nvidias 2xx and ATIs 4xxx series. They actually have your 4850 and a 285 GTX. They also show the difference in performance with the 4850 X2 and the 4870 X2.

    http://ixbtlabs.com/articles3/video/asus-10-p4.html

    Notice the FPS difference between the 4850 and the 285 GTX at the highest and lowest resolutions and with AA and AF cranked up and off.
     
  9. Sep 23, 2009 #8
    My monitor only goes up to a maximum of 1600x1200. I was thinking of buying a Radeon HD 5850 when they officially hit the shelves in October 09. But my CPU will probably choke on it. If your CPU is bottlenecking your GPU, does that only limit the performance of your GPU, and doesn't effect the performance of your entire system?
     
  10. Sep 23, 2009 #9
    My current GPU seems to struggle with S.T.A.L.K.E.R. Clear Sky on 1024x768. Especially when there are a lot of shadows on the screen at once. Such as the beginning of the game for example. Maybe an HD 5850 or GTX 285 will give me smoother gameplay and FPS with those detailed and complex shadows and textures on the screen.
     
  11. Sep 23, 2009 #10
    The 5850 looks like it should be an excellent card for the cost. I wouldn't say your processor will choke on it, but it will hold it back a little. You'll still see big jump in performance if you swap out your 4850 for a 5850, especially if you want to turn up anti-aliasing and anisotropic filtering quite a bit. Even though a relatively slow CPU can hold a video card back a little bit, the great majority of the video work is still being done by the video card. Bottlenecks are a bit exaggerated IMO.
     
  12. Sep 23, 2009 #11
    Either graphics card will definitely yield better performance with AA and AF turned up. Try the commands I gave you to show FPS and post your Stalker results. At 1024x768, even with AA and AF turned up a bit, your 4850 should fly through Stalker. Try turning down the AA and AF a little.

    Do you have the latest Catalyst drivers?
     
  13. Oct 12, 2009 #12
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