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quick question about cpu bottleneck and gpu usage

post #1 of 5
Thread Starter 
hey everyone,

i was just wondering, what constitutes as a bottleneck?

ive had one with crossfired 6870's and a AMD 955 BE, and i was told that it is when your gpu doesnt reach 100% or if your cpu is at 100%.

since i upgraded to i5-2500k, i had to oc my cpu to 4.5 GHz to get rid of any bottleneck i could possibly have. however, when playing crysis, the witcher 2, etc. i have like 30-40% cpu usage(just guessing from eyes) but my gpu's usage never goes to 100%.

is that normal?

i read all the sandy bridge oc guides, and turned off what it told to turn off, ran prime95 for hours upon hours, btw.
    
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post #2 of 5
turn off v-sync

if you want 99% gpu usage
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post #3 of 5
Quote:
Originally Posted by j8ninja View Post
hey everyone,

i was just wondering, what constitutes as a bottleneck?

ive had one with crossfired 6870's and a AMD 955 BE, and i was told that it is when your gpu doesnt reach 100% or if your cpu is at 100%.

since i upgraded to i5-2500k, i had to oc my cpu to 4.5 GHz to get rid of any bottleneck i could possibly have. however, when playing crysis, the witcher 2, etc. i have like 30-40% cpu usage(just guessing from eyes) but my gpu's usage never goes to 100%.

is that normal?

i read all the sandy bridge oc guides, and turned off what it told to turn off, ran prime95 for hours upon hours, btw.
Both Crysis 1 and The Witcher 2 are cpu intensive games, I know for a fact crysis 1 will only use 2 cores, it's probably the same with The Witcher 2 as well.

Your cards are probably as fast, maybe even faster in Crysis 1 than mine (loves texture fillrate since it's all textures) and even at 5.2GHz there is still some minor cpu limitation going on.

That said I still get usage around 99 to 96 percent with frame rates in the upper 70's without AA.


There are only a few games that will ever get close to maxing out a quad core, most games that are threaded past two cores still rely on a single strong core which typically bottlenecks the other threads anyways.
    
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post #4 of 5
Thread Starter 
oh i see,

so for games, itll usually use the most out of one core, then a little bit less of the next and a little less of the next? ive noticed that in task manager as well, but i thought it was just putting weight on random cores.

vsync is already off for the most part of my games, definitely was off when finishing crysis today (which was pretty awesome, i must say). had lag like crazy until i realised that it was my custom TOD mod's fault not deleting models being stored for the ram, deleted it and ran like a dream =].

what is an example of a gpu intensive game that i could try?

thanks for clearing that up, +rep
    
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i5 2500k @ 4.5 GHz 24/7 Asrock P67 extreme4 gen3 XFX radeon 6870 1gb HIS radeon 6870 1 GB 
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4 GB G.Skill 3x seagate barracuda 500GB(2 in raid 0, 1 alone) some asus DVD/ CD + R drive Hyper 212+ in push/pull 
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windows 7 Professional 64 - bit Hanns g 20" 16:9 monitor logitech illuminated keyboard corsair GS 700W 
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Silverstone FT02B G500 17" by 13" mouse pad Logitech S-220 17 Watts 2.1 Multimedia Speaker ... 
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post #5 of 5
Windows does do thread sharing, but games can only use a set amount of cores.. So it may look as if it's using more cores than it actually can because of that.

Anything with a decent amount of tessellation will be pretty gpu demanding on your setup.

Crysis 2, and Metro 2033 (dof) come to mind. You shouldn't have any usage issues with The Witcher 2 assuming you're maxing it out.
    
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