CPU/GPU Bottlenecks.

Hello Tomshardware community. I've been browsing and reading the forums on here for a while and finally decided to make an account.

I wanted to ask you guys about CPU/GPU bottlenecking. Is there a way to test which component bottlenecks the other?

I'm hoping to be able to play StarCraft 2 on at least medium settings by the time of its release and I've been playing the beta and I've experience significant hiccups during large battles.

I've been wondering what was causing this and thought you guys would be able to help out.

My current specs are:

Dell Precision 670
Intel Xeon 3.40GHz (2 Processors)
4GB RAM (well only 3gb usable. Using 32 bit Win7)
ATI Radeon HD 4800.

Here's full graphics card specs.

I've done a few tests in order to find out what was causing the significant drops in FPS.
Using FRAPS I determined that
On ALL highest settings I got an average of 25 FPS.
On ALL lowest settings I got an average of 60 FPS.

During battles, on all high settings it would go down to 10 FPS. On all low settings I got about 25-30 FPS.

Is it possible to determine whether CPU or GPU is bottlenecking from these FPS numbers?

I would appreciate any help!
27 answers Last reply
More about bottlenecks
  1. Not from those numbers, but from those numbers compared to your CPU after you both overclock and underclock it. Find out if there are any major increases/ decreases. Run your test at least 3 times for each so you can see what variances you get.

    An easier way though is to check your CPU usage during gameplay. Run the game in windowed mode or on a separate monitor, and view task manager at the same time. Or you can run task manager and set the refresh speed to low. Then you can play the game, get to the intense part, then either minimize or exit the game and view your CPU usage graph of what it was during your game. If it was at 100% quite a bit, then you have a bottleneck.
  2. Alright. I put it into a windowed mode in order to look at the task manager. During the larger battles the FPS would drop significantly in ultra settings but CPU usage would never go above 50%.

    Would this indicate that my GPU is the bottleneck here?
  3. With that kind of power on the GPU there shouldn't be a problem in terms of graphic processing. An Intel Xeon? Mmm... Looks suspicious to me, since although the load is 50%, doesn't mean that it's not bottlenecking your gaming. But I really don't have any experience in Intel Xeon - ATI combo. Maybe the more experienced guys here can help.
  4. Yeah. I've been watching some of my more battle intensive replays through StarCraft 2 exe and the CPU never goes above 50%. Frame rate drops sometimes to 5 FPS on ultra and like 10 FPS for low.

    I generally have much higher FPS on low settings. Average for ultra is like 20 while low settings can manage about 35-50 FPS.

    Really not sure what's going on here. I know that Intel Xeon's are meant for servers and not really for gaming so maybe the CPU is still the problem. I really have no idea.
  5. The fact that FPS is better with lower settings indicates that the cpu is capable of driving that test to higher frame rates in some cases if you had a faster graphics card.

    The windows task manager showing 50% usage does not necessarily show no cpu bottleneck. That number is across both cores. Each core might be dispatch alternatively from a single task that is 100% utilized. Alternatively, there could be two tasks that are each only partially utilized.

    You might try the following test:

    Keeping your graphics resolution and settings the same, reduce your cpu power. Do this by removing the overclock, or by using windows power management to set a maximum cpu% of perhaps 70%. If your FPS drops significantly, it indicates that your current cpu is a limiting factor, and that a faster cpu would help.
  6. Does anyone know if Starcraft 2 can use more than 1 CPU core?
    Also, you could additionally check GPU usage in catalyst control center. ATI overdrive section.
  7. I think StarCraft 2 is able to run on dual core. Nothing more however.

    Alright so I've done some additional testing. I think a really big culprit was the fact that I had hyper threading on.

    I removed hyperthreading and significant FPS drops were removed.

    During very big battles I was able to hit at least 15-20 FPS with all LOW settings.
    With all ULTRA I hit about 10FPS.

    My CPU usage also hit about a maximum of 70%. (Btw, my power manager... I can't seem to access settings for maximum CPU usage. Only "System Cooling" options show up when I try to change it)

    So perhaps it is a GPU bottleneck. What do you guys think?

    Btw, I want to really thank all of you for replying to my posts! (:
  8. Yep. Now that you've removed the troublesome pentium 4 hyperthreading, it sounds like your GPU is what is holding you back the most. Personally, I would save for a new computer though. If you were to put a better card in there, your CPU would start holding you back.
  9. I'm most likely going to purchase a new computer and new parts within a few months (once school begins again) and so I might as well purchase a decent graphics card now in order to run SC2 and then move that to my new computer.

    Any recommendations?

    I was looking at the HD5770 or maybe the HD4890. Not quite sure. Hmm. What graphics card could I get that's good enough and won't be bottlenecked by my CPU? Maybe I should ask in the Graphics section of the forum.

    But thank you guys SO much for the help. :) I really appreciate it.
  10. I am missing some information here.
    1) Exactly which Xeon 3.4 do you have. I understand them to be single core with hyperthreading. Run CPU-Z to identify it.
    2) Exactly which 4800 graphics card do you have? The GPU-Z does not tell me.
    3) What resolution are you trying to use? It makes a big difference for picking a graphics card.
    4) Exactly what PSU do you have? Brand wattage and model. At least get the amps on the 12v rail or the number of pci-e connectors that it has. The PSU may determine the strongest graphics card that you can upgrade to without a PSU change.

    It does not make sense to me that turning off hyperthreading should make an improvement.

    To access the power settings in windows-7,
    control-panel/power-options/change-settings/change-advanced settings/processor-power/maximum processor state.
    Maximum processor state should be 100%; you can reduce it for testing.

    If you upgrade your graphics card, make it a significant jump of several tiers. Otherwise you will be disappointed.
    Typically, a 5850 or GTX460 class card will give very good gameplay on a 1080P monitor, assuming a decent cpu.
    Upgrading your graphics card first is not a bad idea. You are guaranteed some improvement. Taking that limiting factor out of the equation will give you a better idea of what you need to do with the cpu part.
  11. http://img843.imageshack.us/img843/5884/oiegfx2.jpg

    There we go.

    My Graphics Card is an HD 4850. I've heard from numerous people that it should be good enough to run SC2 on ultra.

    Generally what I've noticed with SC2 FPS was that during HUGE battles (bigger than the ones I originally tested in the above post) the resolution/settings don't really matter. They all drop down to about 5FPS.

    I'm not quite sure what PSU I have. I just know that it is the stock PSU that came with the Dell 670.
  12. I think your problem is the cpu. It is a single core cpu with a very small L2 cache.
    It is an older model which is not nearly as efficient on a clock for clock basis as the nehalem architecture cpu's which are 2 generations more current.
    Even the cheapest i3 clarkdale cpu would be better.

    Your graphics card is quite good. It requires a 450w psu with one 6 pin pci-e power connector. Your PSU obviously has that.
    The 5770 is a marginally stronger card that could use the same PSU. Such a small difference is not worth the upgrade. If you are looking at a 5850 class card, which is a meaningful upgrade, you will need 500w psu with two 6 pin connectors. Such cards may also be longer, and you need to make certain that it would fit in your case.

    I think it is time to consider a new build.
  13. Thats a Pentium 4 550 with a prettier logo!
    Definitely worth an upgrade.
    A cheap option is getting an Athlon X3, OC it and you'll see a major jump right there.
  14. He has two. They should perform like an Athlon 64x2 at about 2.2GHz
  15. Nonetheless, I do think my CPU is the problem to a certain extent. It was time for an upgrade anyhow.

    Thank you all for the help guys! I guess I'll be purchasing a new mobo, cpu, ram, and psu.

    I think I'll keep my current gfx card.
  16. enzo matrix said:
    He has two. They should perform like an Athlon 64x2 at about 2.2GHz

    I'm not sure SC2 can take advantage of a dual processor setup. The CPU usage graph looks like its showing that.

    Besides, even an AX2 2.2Ghz is slow by today's standards and (two) 90nm Netbursts would suck power like crazy so an upgrade would do him lots of good.
  17. So I decided to build a new computer and buy some parts from NewEgg.

    This is what I currently have in my cart. I'd love your guys' opinion.

    G.SKILL 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1333

    AMD Phenom II X4 945 Deneb 3.0GHz
    OCZ ModXStream Pro OCZ600MXSP 600W

    Rosewill ATX case

    Also, I'll just continue to use my HD4850.

    I already have mouse/keyboard/hdd/etc so I won't be needing those.

    Would all these work out fine? These parts are all compatible right? Would I be able to run SC2 on at least high-ultra settings?

    Thank you!
  18. ^ I love it. It's perfect. I have the same power supply lol.
    I'd look into replacing your old hard drive anyway though.
  19. Ahh. My old HDD. I only got it recently and so I'm a bit hesitant to replace it right away. Poor thing didn't even see half of it fill up so far.

    I'll keep it for now. ^^

    Thanks for your input guys. I really appreciated everything you guys have done.

    Now I'm off to finally purchase my parts and be playing StarCraft 2!

    Thank you!
  20. Look good.

    Heres a better case (IMO) for the money: http://www.newegg.com/Product/Product.aspx?Item=N82E16811146058&Tpk=Nzxt%20m59

    And an Ax4 alternative if you want to save a few bucks, L3 cache in gaming isnt THAT important.
  21. HarUOne said:
    Ahh. My old HDD. I only got it recently and so I'm a bit hesitant to replace it right away. Poor thing didn't even see half of it fill up so far.

    Lol. I assumed it was an old IDE drive. Nevermind then :D
  22. Timop said:
    And an Ax4 alternative if you want to save a few bucks, L3 cache in gaming isnt THAT important.

    Do you have anything to back up that statement considering it contradicts everything I've heard and read? I would test it myself, but I only have an Athlon IIx4 at 3.22GHz. No Phenom IIs in sight :p
  23. enzo matrix said:
    Do you have anything to back up that statement considering it contradicts everything I've heard and read? I would test it myself, but I only have an Athlon IIx4 at 3.22GHz. No Phenom IIs in sight :p

    I meant it doesn't help enough to justify the price increase, thus "THAT" was capitalized. Never said anything about it not helping, it is nice when you have $200 to spend on a CPU.

    Point is, an AX4 635@3.2 Ghz would perform like the 945@3.0Ghz, just for $50 less.
  24. Timop said:
    I meant it doesn't help enough to justify the price increase.

    Oh I misunderstood. Well, as you can see by my processor choice, I agree.
  25. I've been trying to read up on whether the L3 cache have major impact on performance and here is what I came up with.


    It seems like it's fairly marginal right now. Is it really worth getting the L3 cache? There's a $40 dollar difference between the Anthlon and the Phenom. What do you guys think? Please keep in mind that I'll just be needing to run StarCraft 2 without hiccups. Not looking to run anything like GTAIV, Crysis, or any other future games coming up XD.
  26. ^ well, I'm agreeing that it's not worth the extra cost and the 2.9GHz Athlon IIx4 is a good CPU at a great price.
    I can also say that for sure it will be all you need right now.
  27. Alright then! I'll go with the Anthlon IIx4. Whew. Now that's all done and over with. Again thank you guys so much. Tomshardware truly has one of the best communities on the internets haha. Thanks guys.

    And Timop, I've decided to go with the case you suggested as well.

    Thank you!
Ask a new question

Read More

CPUs GPUs Bottleneck Product