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Cpu bottleneck

Last response: in Graphics & Displays
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January 24, 2010 11:47:19 AM

last time i wrote this firefox erased everything so this will be more abbreviated.

ok, i built my little brother a computer. a quad core athlon 620 and a ati hd4850

he got fallout, one of the games that is in the benchmarks so i looked it up.

he plays at 1024x768 no aa no af, and gets 30fps about. i dont konw if the graphics card is the 1gb version ofr the 512mb version, but lets assume 512mb.

either way, he gets lower fps at 1024 than the benchmark did at 1920x1200 with 8aa and 15af

i want to know if this is a cpu bottleneck or not,

because when i built the computer i had a choice between the quad athlon or the dual phenom, and i looked at my computer, which didn't have l3 cashe, and it could play most games pretty damn good. i thought that the people who said that the 620 was bad for gaming were the same people who say aa is necessary at 1920x1200 because of all the jaggies.

did i make the wrong decision or is there something else, because this looks like the performance is WAY to low.

if you want more details ill give them, i just didn't want to rewrite all i did last time in case this just all gets erased again

More about : cpu bottleneck

January 24, 2010 1:15:09 PM

there is also oblivion, that he heavily modded and at 1024x768 with no aa or af barely goes above 20fps, and barely above 12 in rain

what would you suggest i try? it would have to be a demo, i wouldn't pay retail for something just to benchmark his computer
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a c 189 U Graphics card
January 24, 2010 1:27:36 PM

^+1
Have u tried the latest driver?
U might want to try the older one or driver in the CD if that above doesn't work well.
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January 24, 2010 5:25:49 PM

ok, getting that, sadly its about a 3 hour wait
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January 24, 2010 5:27:58 PM

are there any clear sky benchmarks i here that i can see? the only time i ever remember seeing that game in benchmarks is when its a specific card
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January 24, 2010 10:20:04 PM

ok that stalker benchmark with maxed everything at 1600x1200 is getting between 12-20fps, mostly around 17. anyone know if thats good or not?
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a c 84 U Graphics card
January 25, 2010 12:17:12 PM

http://www.techpowerup.com/reviews/Powercolor/HD_5770_P...

it's about right as far as I can tell... they used i7920@3.8 so that might explain why it's couple of frames higher than yours (used 4870 values minus some :p ), though stalkers are very gpu limited games

edit: hmm they don't say whether they used the benchmark or some actuall game play though...
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a c 130 U Graphics card
January 25, 2010 12:26:02 PM

Have you tried playing fallout at a higher resolution ? It dosent always work out that just going for the lowest resolution will equal the fastest performance.

Mactronix
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January 25, 2010 8:02:44 PM

the only time i ever had that happen was when the program was extremely poorly coded.

ill try, i may not be able to get to do it today,
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a c 216 U Graphics card
January 25, 2010 8:14:17 PM

It's not always poor coding that causes the resolution to not make much if any difference. Often that's a result of the CPU bottlenecking and the GPU is not on either resolution.
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January 25, 2010 9:23:34 PM

so if a game is on a lower resolution, the cpu wont let the game render it faster?
i may just be completely reading that wrong but thats what it sounds like
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a c 130 U Graphics card
January 25, 2010 9:42:25 PM

Ok i will try and explain it but a lot of people even those who claim to know every thing dont seem to under stand it.
There is a possability that you are causing an artificial CPU bottleneck by using such a low resolution.
Its a lot easier if you just try it at a higher res and see if it makes a differance but the theory behind the sugestion goes like this.
Running at a lower resolution gives the GPU a lot les to do as it has less dots/pixels to draw, its a bit more involved than that but im trying to keep it simple. The CPU still has the same work load regardless of the resolution so by giving the GPU less to do you are giving the CPU less time in effect to do what it needs to do.
Say for example the CPU can generate the information the GPU needs to render the frames at a rate that equates to 60FPS at 1680x1050 and your GPU can render frames at 55 FPS at that resolution then all is fine as the GPU isnt waiting on info to do its job.
If you reduce your resolution to 1024x768 then it should be clear to all that the GPU can render that faster than it could at 1680x1050.
Where you get the problem is if you are asking the CPU which can render at 60FPS to now try and keep up with your GPU which because its not drawing so many Pixels can run at 75FPS then its restricted to what the CPU can deliver.
Its not as black and white as it will now just render at 60 FPS as the bottleneck causes issues which make the card skip frames etc to try and keep up and you get a cumalitive effect which means what you actuially see is less than the CPU max.
It gets worse if you have V-sync on (please tell me you dont) as this will run to multiples or intrergers of 60 which could end up reducing your actual FPS by a quarter or even a half.

Mactronix
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January 25, 2010 10:16:25 PM

ok i see what you are saying,

basically, if the gpu can render it at 100fps but the cpu can only handle 50, the gpu ony goes to 50.

now here is where my problems are with how the games are running, its at a low rez, but that shouldn't effect how fast the game can run. as i have found out that the athlon he has and a phenom are more or less = at least in terms of what he had available for options.

i dont know if vsync is on or not. ill have to check when i get a chance.

but just a bit ago, i installed a game called gunz the dual, not the best game, but a fun one that me an him can both play. i have fraps up and his computer is running the game at close to 700-1000fps. at points getting close to 2000.
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a c 130 U Graphics card
January 26, 2010 7:06:32 AM

All games are not equal so saying one will run fast dosent really mean anything, best thing to do is to increase the res and see if it goes any faster or not.
It wont all of a sudden shoot up but if increasing the resolution gives you say 5-10 more FPS that will indicate that what i have described was happening.
If it dosent or drops then thats that ruled out.
I suggest you try 1280 x 1024 and 1600 x 1200 or as close as you can get and just check to see if you get any improvement. Even if you get no increase running at a higher res will give you a better picture.

Mactronix
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January 26, 2010 7:41:49 AM

yes and no,

in a video game anything over 1024x768 gets harder and harder to read text, i dont think he will care to much either way though.

when im able to try ill post back here
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!