GTX 970 bottleneck question.

Discussion in 'Videocards - NVIDIA GeForce' started by IceVip, Oct 23, 2014.

  1. IceVip

    IceVip Master Guru

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    I was wondering, my fx 8320 is at 4.8ghz right now aaaand i wanted to know
    if a gtx 970 can be too fast for my cpu.

    Now i want to point out something, Dota 2, maxed out at 2048x1152, with an
    r9 280X my gpu usage almost never hits 99%, it usually goes from 70 to 90%
    .. why is that? the cpu is at 20-35% usage, that's not bottleneck, is that
    optimization issues? The game is made to use 4 cores so it shouldn't be having
    this problem, plus dota 2 is not the only game, my gpu never hits a stable 99%
    in half of the games i play, but the cpu never goes above 50% usage so its not
    throttling thus.. its not the cause for the gpu usage to not be 99% all the time..? and if i have such issues with r9 280x..
    i was wondering would they magnify if i get an even more powerful gpu.

    P.S Its funny how i had to buy this mainstream 7970+8350 like config, to find out
    that there's something wrong with it in terms of how the two components work togather..
     
  2. Corbus

    Corbus Ancient Guru

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    You will be fine. But are you sure you need a new gpu? Playing dota2 and all...
     
  3. IceVip

    IceVip Master Guru

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    I play bf4 a lot, with mantle on i don't have the slightest problem, but i always
    have problems with ENB in games n sh.. so yeah i wanna move to nvidia finally.
    But I'm just not so sure why people say this cpu is a bottleneck when it isn't even
    close to reaching 99% usage, but the other mystery is why the gpu is not 99%
    if the cpu is not 99%.. I always understood that bottleneck is like, if cpu is
    99% then the gpu would have lower usage cuz the cpu is struggling, if someone
    can explain to me why this is happening i would be really thankful..
     
  4. ---TK---

    ---TK--- Guest

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    It would be a big bottleneck in multi gpu. Single 970 is fine.
     

  5. spider

    spider Guest

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    Because its cpu-time and not frame-time
     
  6. Pill Monster

    Pill Monster Banned

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    You said u were going to RMA that card, what happened?
     
  7. sykozis

    sykozis Ancient Guru

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    It's not really a "bottleneck" issue. It's a latency issue. AMD still has the PCIe controller built into the chip. It takes longer for AMD systems to send data from the CPU to the GPU because it has to be sent to the chipset first and the chipset then relays it to the GPU.
     
  8. IceVip

    IceVip Master Guru

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    Still waiting for an answer, but I'm pretty sure ill get the money back and buy the 970
     
  9. Pill Monster

    Pill Monster Banned

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    CPU load doesn't tell the whole story. 50% might mean 4 cores at 100%, u need to look at core load to see what's really going on.

    Games like DOTA aren't overly taxing on GPU's anyway, try playing FC3 in DX11....
     
    Last edited: Oct 23, 2014
  10. IceVip

    IceVip Master Guru

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    I remember having odd usage in that game too, it was like
    60-80% usage and the cpu was still 25-30%, all cores were utilizing.
     

  11. CPC_RedDawn

    CPC_RedDawn Ancient Guru

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    Yep pretty much what Pill said.

    It all depends on how the game is coded. Some games will only use 1 core, 2 cores, or 8 cores.

    The game engines if coded properly will scale things down and run multiple data streams over a single core if the game say was coded to use 4 cores but you only have 2 cores installed it will use those two cores but run more data through them.

    If a game uses 4 cores at around 50% each and you have a 4 core CPU (no HT) that is still only 50% overall CPU usage as half the each 4 cores is not being used.

    Then you also have to factor in graphics settings, most things like bump mapping, particle effects, dynamic lighting and shadows will all be thrown to the GPU as this is what they are built for. But it all boils down to the type of game, if the game is not graphically demanding maxed out you can make it more graphically demanding and raise the resolution adding more pixels to be rendered each frame or you can add in more AA to add even more processing time to each frame for the GPU to handle.

    Games like RTS, MMO, or heavy physics based games will have a lot of A.I to calculate which is done mainly on the CPU. Hence why in games like DOTA, LOL, Warcraft, Starcraft, Company of Heroes, etc they use more CPU time for each frame as the A.I is being done on the CPU but the GPU is not really needed very much as the grahics even maxed out will not tax the GPU much.

    Then it all boils down to refresh rates, if you have a 60Hz monitor and the games graphics in question are easy for the GPU to render you will get 60fps but around 30% GPU usage but the A.I calculations always stay the same and if you CPU isn't up to scratch (ie not enough GHz or cores) then the game will still slowdown as the GPU is waiting for the CPU to catch up. This can cause stuttering.

    If you turn off VSYNC and allow the frame rate to go nuts you will get 99% GPU usage even in games like DOTA as the GPU is allowed to render as fast as it can. This can cause even higher CPU usage as the A.I may stay the same but the GPU is asking the CPU for more data as its producing 100's of frames a second in games like DOTA which the CPU probably can't handle if its a low end model (or not enough GHz or not enough cores) this will then produce low GPU usage as the GPU sits waiting for the CPU to catch up hence a CPU bottleneck.

    GPU bottleneck is the other way around, not so much A.I or physics happenning but if you have tons of AA, high resolution, particles, and other graphical effects you will reach the GPU's limit and get 99% usage on the GPU as its being over worked but then the CPU usage will go down as it then sits waiting for the GPU to get done rendering a frame. Hench a GPU bottleneck.

    Hope I explained this better and I hope this helps.

    With your CPU at its clock speed and a GTX970 you will be fine, but then again remember even if its fine in one game that is coded properly to use mutliple cores and a decent amount of GPU does not mean all games will be the same. Games that have been poorly optimized will still only use as many cores as they have been coded to use.

    Windows 8 helps that a little as it has much better core scheduling than Windows 7 does, and have better memory management too. Which is why a lot of games run smoother in 8 than 7.
     
  12. jimdove

    jimdove Guest

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    I have nothing to say on this subject other than I am about to add Mint choc chip Ice cream to my face :D
     
  13. IceVip

    IceVip Master Guru

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    I'm not in the mood for that :D
     
  14. spider

    spider Guest

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    Not enough you have to look at the frame times.
    The cpu is simply not fast enough to finish its job in time. Cpu time gives you no information about that.

    [​IMG]
     
  15. IceVip

    IceVip Master Guru

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    You explained yourself perfectly but it was not exactly about what i asked.
    Imagine this:
    cpu:
    core 0 10%
    core 1 20%
    core 2 20%
    core 3 30%
    core 4 0%
    core 5 0%
    core 6 0%
    core 7 0%

    gpu usage: 70-80%

    If the game is optimized to run on 4 cores, and those 4 cores
    are not struggling, why is it that the gpu is not hitting 99%?
     

  16. spider

    spider Guest

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    Hitting framelimit eg vsync or CPU is bottlenecking.
     
  17. Pill Monster

    Pill Monster Banned

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  18. IceVip

    IceVip Master Guru

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    Naa screw the throttle, i had this with my HD7870 which had no throttle, and i had this now, i remember the problem was really visible in far cry 3, thought switching
    from 7870 to r9 280x might help but the only thing that changed was the usage
    it just dropped down.
     
    Last edited: Oct 23, 2014
  19. Pill Monster

    Pill Monster Banned

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    He was asking about CPU bottlnecking not frame latency. The two are mutually exclusive, high frame latency can happen with or without a CPU bottleneck.


    Op u should see what happens with your RMA before worrying about GPU load imho.... Good luck. :)
     
  20. spider

    spider Guest

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    I wasnt talking about frame latency I was talking about CPU frame times and these CPU frame times are bottlenacking the GPU if they are higher than the GPU frame times.

    Looking in the task manager for CPU time in % is mostly nonsense.
     

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