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  1. #1
    Joined
    Dec 2003
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    107

    CPU bottleneck on a GPU upgrade?

    I built a new budget-ish machine last year during Black Friday sales and carried over the video card from the prior rig (Radeon HD 6970, noted below with specs). Haven't really used it much because PC games out in the past year haven't caught my attention. I wanted to be able to run 4K one day, but didn't see it really happening with the GPUs/tech at the time (or in my budget at that moment) so didn't design it with that in mind. Fast forward to today when Civilization 6 and Planet Coaster are arriving, and my interest in PC gaming has been rekindled and I'm reviewing my options.

    Basically, I'm contemplating if I'm in a good position to move to a 4K setup with this current machine. Essentially, I'm wondering about putting a GTX 1080 in place of the Radeon 6970 and whether I could achieve reasonable 4K performance with the CPU I currently have: a (currently stock) AMD 8320 paired with a Hyper Evo 212.

    I'm not interested in some type of AMD/Intel debate on this: just looking at what I've got and whether I can achieve solid 4K performance in the types of games I like to play (not currently into the first person shooter scene) with that GPU upgrade. I'm posting in the CPU forums because that seems to be the biggest potential bottleneck in my specs.

    Current specs:
    AMD FX-8320
    Cooler Master Hyper 212 EVO
    ASUS M5A99FX PRO R2.0
    Corsair Vengeance Pro 16 GB (2x8GB) DDR3 1866
    Sapphire Radeon HD 6970 2GB (Looking to upgrade this to Gigabyte GTX 1080)
    SanDisk Ultra II 480GB SSD
    Corsair RM650X 650W Power Supply
    Corsair Carbide Series 500R Case

    Thanks!

  2. #2
    Joined
    Mar 2003
    Location
    Central NJ
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    11,091

    Re: CPU bottleneck on a GPU upgrade?

    Quote Originally Posted by steeldestroyer View Post
    I built a new budget-ish machine last year during Black Friday sales and carried over the video card from the prior rig (Radeon HD 6970, noted below with specs). Haven't really used it much because PC games out in the past year haven't caught my attention. I wanted to be able to run 4K one day, but didn't see it really happening with the GPUs/tech at the time (or in my budget at that moment) so didn't design it with that in mind. Fast forward to today when Civilization 6 and Planet Coaster are arriving, and my interest in PC gaming has been rekindled and I'm reviewing my options.

    Basically, I'm contemplating if I'm in a good position to move to a 4K setup with this current machine. Essentially, I'm wondering about putting a GTX 1080 in place of the Radeon 6970 and whether I could achieve reasonable 4K performance with the CPU I currently have: a (currently stock) AMD 8320 paired with a Hyper Evo 212.

    I'm not interested in some type of AMD/Intel debate on this: just looking at what I've got and whether I can achieve solid 4K performance in the types of games I like to play (not currently into the first person shooter scene) with that GPU upgrade. I'm posting in the CPU forums because that seems to be the biggest potential bottleneck in my specs.

    Current specs:
    AMD FX-8320
    Cooler Master Hyper 212 EVO
    ASUS M5A99FX PRO R2.0
    Corsair Vengeance Pro 16 GB (2x8GB) DDR3 1866
    Sapphire Radeon HD 6970 2GB (Looking to upgrade this to Gigabyte GTX 1080)
    SanDisk Ultra II 480GB SSD
    Corsair RM650X 650W Power Supply
    Corsair Carbide Series 500R Case

    Thanks!
    Have you considered overclocking? I suspect you will see some bottlenecking (especially at stock), but 4K on a single 1080 is still a tough task for the GPU. Even if you weren't GPU limited you might not be thrilled with the results. Depends on the games and what your expectations of performance are.


    Trust me, I do science
    My Hardware, Past and Present

  3. #3
    Joined
    Dec 2003
    Posts
    107

    Re: CPU bottleneck on a GPU upgrade?

    Quote Originally Posted by Activate: AMD View Post
    Have you considered overclocking? I suspect you will see some bottlenecking (especially at stock), but 4K on a single 1080 is still a tough task for the GPU. Even if you weren't GPU limited you might not be thrilled with the results. Depends on the games and what your expectations of performance are.
    Thanks for the response! Just to clarify, what are you thinking I would overclock, the CPU or GPU?

    To the rest of your post:
    My understanding is that a single 1080 runs games well on 4K, albeit not always at ultra settings. Is that not the case?

    More specifically, the only GTX 1080 benchmark for Civ 6 I could find puts the 1080 at around 70 fps on ultra settings for 4K, which seems sufficiently playable to me (particularly for that style of game) since I'm not targeting a monitor above 60Hz. That is, of course, on an Intel i7, and per my original question.

  4. #4
    Joined
    Jun 2012
    Posts
    164

    Re: CPU bottleneck on a GPU upgrade?

    Quote Originally Posted by steeldestroyer View Post
    Just to clarify, what are you thinking I would overclock, the CPU or GPU?
    I believe Activate: AMD was referring to OC'ing the CPU. The 8320 will most likely be the bottleneck when paired with a 1080, especially with games that are single-thread based and not optimized for a multi-threaded CPU. In general, the FX series are good overclockers so any extra speed you can muster from the CPU will reduce the amount of the bottleneck. It's worth mentioning that if Civ 6 is optimized for multi-threaded CPUs, that would only help the 8320.

    And you're correct, the 1080 is the best single GPU option right now for 4K gaming. BUT! like you said, it may not get you 60 fps with max settings.

    Hope this helps.

  5. #5
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    Central NJ
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    11,091

    Re: CPU bottleneck on a GPU upgrade?

    Quote Originally Posted by btdog View Post
    I believe Activate: AMD was referring to OC'ing the CPU. The 8320 will most likely be the bottleneck when paired with a 1080, especially with games that are single-thread based and not optimized for a multi-threaded CPU. In general, the FX series are good overclockers so any extra speed you can muster from the CPU will reduce the amount of the bottleneck. It's worth mentioning that if Civ 6 is optimized for multi-threaded CPUs, that would only help the 8320.

    And you're correct, the 1080 is the best single GPU option right now for 4K gaming. BUT! like you said, it may not get you 60 fps with max settings.

    Hope this helps.
    Pretty much this. I'm thinking the 8320 will be bottlenecking a 1080 at stock... maybe even while overclocked, but definitely less so. Just FYI, but the CPU at the clocks in the TPU review is roughly 2x as fast as the 8320 when overclocked (http://www.anandtech.com/bench/product/1403?vs=1548). as btdog mentioned, the degree of bottlenecking will depend a lot on how well the game handles multithreading, as single threaded performance on the 8320 is just not that great.

    Looks like Civ does reasonably at 4K on a 1080, though I'd just caution that single values for average FPS don't necessarily give the whole picture (min FPS tends to be just as important, if not more so, than avg). I think you could have a decent experience playing slower paced games at 4K with your CPU right now, though you may find yourself hitting a wall and continuing to wonder just how much the CPU is holding you back. The plus side is that 4K is going to be hitting your GPU so hard that the benefit from a new CPU might be smaller than we all think.

    It sounds like you're hunting for advice about whether or not you should re-build the rig with a new CPU/mobo/GPU combo or if a nice high end GPU upgrade will do the job for now. I think the answer to that probably depends on how long you think you'd be sitting on your existing CPU before you upgrade, what your budget is, and how long you hope to have this GPU for. Truth be told if I were in your shoes I'd probably just get the fancy GPU, get a huge performance boost and start budgeting for a CPU/mobo upgrade as soon as possible after that.
    Last edited by Activate: AMD; 11-14-2016 at 01:14 PM.


    Trust me, I do science
    My Hardware, Past and Present

  6. #6
    Joined
    Dec 2003
    Posts
    107

    Re: CPU bottleneck on a GPU upgrade?

    Thank you all for your thoughts — extremely helpful.

    I spent some time over the weekend doing an overclock on the 8320. I hit 4.2Ghz on stock voltage without much effort, but backed it down to 4.1Ghz because Prime Small FFTs was hitting max temp on the socket after 15 min. I decided to just stick with 4.1Ghz (not mess with additional cooling for now), and ran Prime Blend for 24 hrs with no errors or issues.

    I typically keep GPUs around quite awhile (the 6970 I have now I bought back in 2011 when Civ 5 came out —•has it really been that long?), so I'd expect something similar here.

    Quote Originally Posted by Activate: AMD View Post
    Truth be told if I were in your shoes I'd probably just get the fancy GPU, get a huge performance boost and start budgeting for a CPU/mobo upgrade as soon as possible after that.
    I've actually been coming to the same conclusion. I've now put a Gigabyte GTX 1080 on order. For the future, what's the best way to tell that the CPU is the primary bottleneck holding back the GPU when running a specific game or application (vs. just the nature of the 4K resolution the GPU has to push)? Is there a good way to determine that?

  7. #7
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    Re: CPU bottleneck on a GPU upgrade?

    Quote Originally Posted by steeldestroyer View Post
    Thank you all for your thoughts — extremely helpful.

    I spent some time over the weekend doing an overclock on the 8320. I hit 4.2Ghz on stock voltage without much effort, but backed it down to 4.1Ghz because Prime Small FFTs was hitting max temp on the socket after 15 min. I decided to just stick with 4.1Ghz (not mess with additional cooling for now), and ran Prime Blend for 24 hrs with no errors or issues.

    I typically keep GPUs around quite awhile (the 6970 I have now I bought back in 2011 when Civ 5 came out —•has it really been that long?), so I'd expect something similar here.



    I've actually been coming to the same conclusion. I've now put a Gigabyte GTX 1080 on order. For the future, what's the best way to tell that the CPU is the primary bottleneck holding back the GPU when running a specific game or application (vs. just the nature of the 4K resolution the GPU has to push)? Is there a good way to determine that?
    Watch your CPU and GPU usage in game. If your CPU is pegged at 100% on one or more cores consistently while the GPU usage is under 100%, that would be a telltale sign. Theres a few other non-scientific things you can do, like adjust resolution up and down and watch the relationship between GPU and CPU usage. As you reduce resolution the CPU tends to take over as the limiting factor, so the further down in resolution you can go before the CPU gets maxed, the less likely it is to be holding you back at higher resolutions. You can also compare framerates and GPU usage as a function of CPU speed. Put your CPU on stock clocks and note framerate, then OC and see how much it goes up. If the relationship is pretty strong (i.e. 10% clock speeds = 10% FPS increase) you're probably CPU limited

    good luck, I'm sure you'll see a huge improvement with the 1080 one way or the other


    Trust me, I do science
    My Hardware, Past and Present

  8. #8
    Joined
    Dec 2003
    Posts
    107

    Re: CPU bottleneck on a GPU upgrade?

    Quote Originally Posted by Activate: AMD View Post
    good luck, I'm sure you'll see a huge improvement with the 1080 one way or the other
    Thanks! Awesome info. Will keep an eye on the usage you mentioned.

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