please help me find the bottleneck

I apologize if I opened the thread in the wrong section. I was confused.

Config:
AMD FX 6100 @ 4.2GHz
AMD Radeon 7850 2GB on Catalyst 13.3B
1X 4GB DDR3 GSkill Sniper Memory
Gigabyte GA-78LMT-S2PT Motherboard
Seasonic S12II 520 Watts PSU

For some reason I am not getting 99% gpu utilization in many games like Far Cry 3, Crysis 3, GTA 4 and Skyrim. Overclocking the CPU gave me some ~3-4fps improvement in some areas, but that's for a 1GHz OC of the CPU.

Here is a screenshot of FC3 in an area where this problem happens.
http://s16.postimg.org/vo2a8ulcx/Untitled.jpg

77% GPU usage, 52% CPU usage

Note that GPU usage is not always this low. Sometimes it jumps to 95-92% but rarely 99% in FC3. PS: Vsync is turned off. I am playing @ 1080p. There is no thermal throttling.

It is the worst in Assassin's Creed 3 and GTA 4 where I get only about 30% gpu usage and 19-25FPS which makes both of them almost unplayable.

My question is that am I being CPU limited? or is it happening because of something else. I am using only a single stick of 4GB GSkill Sniper 1600 (OC'ed to 1866) memory. So does single channel vs dual channel have a huge performance hit?

Thanks.
5 answers Last reply
More about find bottleneck
  1. well for starters games cant really use 6 cores efficiently, you'd be lucky to find a game that uses 4 threads, 2 is most common these days afaik. So you might still be cpu bottlenecked even when the load% is 'low'... thou the 1GHz oc should have helped a lot more if this truly was the case here. You could test this by disabling cores in the bios and see how the performance scales with core count, basically once you get more cores running than the game has threads the performance levels out and more cores don't give any more fps or higher gpu usage.
    Single channel ram is not doing any good either, try getting a second stick in there. On Intel machines going from dual to tripple channel didn't matter much but it might be different case with single vs dual... haven't seen any benches thou.
  2. Kari said:
    well for starters games cant really use 6 cores efficiently, you'd be lucky to find a game that uses 4 threads, 2 is most common these days afaik. So you might still be cpu bottlenecked even when the load% is 'low'... thou the 1GHz oc should have helped a lot more if this truly was the case here. You could test this by disabling cores in the bios and see how the performance scales with core count, basically once you get more cores running than the game has threads the performance levels out and more cores don't give any more fps or higher gpu usage.
    Single channel ram is not doing any good either, try getting a second stick in there. On Intel machines going from dual to tripple channel didn't matter much but it might be different case with single vs dual... haven't seen any benches thou.

    Thanks.

    I had tried disabling 2 cores in the bios and taking my clock speed upto 4.4Ghz but it did not make much of a difference. Also, while it is not the best cpu very less peeps have said that it is a bottleneck for their cards and I've seen some using it in Crossfire config's so I dont think it is the case.

    I was saving money on an SSD. Too bad I'll have to use it on RAM now :(

    Waiting for more input tho.
  3. A good way to test for CPU holding you back in times when the frame rates drop is to run a benchmark using fraps with anti aliasing off, and then run the same one with full scene AA on.

    At first glance, just check your min/avg/max numbers. If they all shift downward by a similar percentage then your video card is causing the problem. If your min remains pretty much the same, but your max and average drop then your CPU is causing the slow down.

    The theory being is that because AA is a highly GPU dependent task in times where the CPU can't send the frames to the video card fast enough then the video card has plenty of time to do all the AA before the next frame anyway. In times where the CPU is able to send scenes fast enough the video card is plugging away trying to keep up pumping pixels out.

    Oh, and also, if you have an AMD CPU, it's your CPU ;)
  4. Ok, so Far Cry 3 apparently makes use of 4 threads max. Setting it to use 3 cores in CPU affinity gives a performance hit while increasing the usable cores to 5 does not increase performance.

    I have noticed that even in this situation, my CPU usage is not maxing out. While running 4 cores with FC3 in a bottlenecked state the cpu usage reaches 70-85% tops.

    So is it time to add another stick? Is anyone here with a single channel memory configuration into gaming?
  5. Did you try the AA/Res scaling test?
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