670 in 3D, not fully utilized?

[cookybiscuit]

I've noticed quite a bit that when playing in 3D, frames can drop below the cap, and the GPU won't max out its usage, CPU usage doesn't go anywhere near topping out either. Dropping ingame settings only decreases usage, and doesn't effect FPS.

Why is this?

Thanks.

 

[EzioAs]

Your CPU is probably bottlenecking the 670. What's your CPU?

 

[cookybiscuit]

i5 2320, doesn't bottleneck in 2D and 3D only really hits the GPU, so I'm doubtful.

 

[EzioAs]

Just to be clear, 3D games will still depend on the CPU as well and a low-end CPU will bottleneck a high-end video card. However, that doesn't seem to be the case here or it could be because I haven't seen any reviews on the i5-2320. So it may or may not bottleneck your 670. Can you post some 3DMark 11 (or any other graphics benchmark, games) results?

 

[cookybiscuit]

http://www.3dmark.com/3dm11/5533736

and holy crap I just realised how crappy my RAM is.

 

[EzioAs]

Your 3DMark 11 P score is a little bit lower than normal. Most 670 will score 8100+ in 3DMark11 Performance.

What RAM are you using.

 

[cookybiscuit]

4,096 MB Ramaxel Technology DDR3 @ 667 MHz

670 is OC'd to 1254Mhz, and heres a Unigine score if its worth anything.

http://i.imgur.com/BQ9jn.png

Its usually a tiny bit higher (52/53) but I forgot to turn off my frame limiter in Afterburner before I started, so FPS is limited to 117.

 

[EzioAs]

Where did you get the 667MHz speed? Is it the exact name or from CPU-Z?

 

[cookybiscuit]

Thats just what 3D Mark 11 says it is.

 

[EzioAs]

Download CPU-Z (this is a necessary tool for PC) and look at the memory speed. I believe your actual speed is 1333MHz though 3DMark reported 667 because it's DDR (Double Data Rate).

1333MHz memory does bottleneck the CPU in many cases if memory serves me right.

 

[cookybiscuit]

http://i.imgur.com/JBZBi.png

 

[EzioAs]

yeah that's 1333MHz.

 

[cookybiscuit]

Thanks for the help.

So will that cause a problem? I don't know a great deal about it but thought RAM didn't matter too much, and 1333 seems pretty standard. Its taken from a prebuilt system though which is why its crappy.

 

[EzioAs]

Are you using the latest geforce driver? Perhaps it could solve your issue. Anyway, I forgot to tell you that in most cases, you're not going to see the CPU usage max out in games.

 

[cookybiscuit]

310.90, had this issue since starting to use 3D. I know CPU shouldn't top out but I just don't get why in 3D I can lower the settings and rather than FPS increase usage goes down.

 

[EzioAs]

That's because when you lower the settings, the GPU has to process less. You don't see much if any performance increase is a clear cut example of a cpu bottleneck although I don't think it's too bad

 

[cookybiscuit]

I'm not sure what you mean. I get it has to process less, but why wouldn't the framerate go up? This happens even in really old titles, for example I struggle to hold 30FPS in True Crime, it came out like 8 years ago. I'm kind of wondering if its just if some games and 3D don't get along.

 

[EzioAs]

Borrowed this from overclock.net forums

What goes on when you play a game. Simplified

- The CPU sends draw calls to the graphics driver, These draw calls could be anything from rendering a little tree to a mega battle with loads of explosions.

- The graphics driver then turns the draw calls into a scheduled rendering list and feeds it to the graphics card.

- The graphics card renders the list sent to it by the graphics driver.

My quite rubbish explanation

Now as we all know CPU's have varying amounts of power, And we also know that games don't just consist of graphics.

There's sound, Physics, artificial intelligence and general game management code all running and requiring processing at the same time that these graphics draw calls are being processed.

Now if a large part of a CPU's resources are being consumed by sound, physics or artificial intelligence then there's not a lot of spare CPU processing cycles left over for processing the draw calls.

Now if you have a relatively weak graphics card this isn't a problem as the CPU could easily keep the graphics driver and thus, The graphics card fed with rendering information.

Now throw in a high end graphics card and you're in trouble, With the CPU using it's processing power on other aspects of the game the monster GPU is sat idle waiting for rendering information.

And that is a CPU bottleneck.

It's also the reason why games benefit from quad core support as there's more cores and CPU cycles to generate these draw calls while other cores handle other aspects of the game.

How to tell if you're CPU bottlenecked :

- Running at higher resolutions doesn't affect your frame rate.
- Low GPU usage
- High GPU usage with low on screen action but usage drops when loads of enemy's/physics work loads are being processed on screen.
- Adding a second or third graphics card has provided no change in frame rates

What to do if you're CPU bottlenecked :

- Overclock your CPU
- Upgrade CPU
- Turn off as many back ground programs as possible to try and free up some CPU cycles
- Turn up graphics settings to try and move the bottleneck over to the graphics card by giving it more work to do.
- Turn up anti-aliasing ( Works best for me )


Original link: http://www.overclock.net/t/953305/how-does-a-cpu-bottleneck-a-graphics-card

 

[cookybiscuit]

I ran HWinfo32 in Assassins Creed 2 (a game where I experiance this), usage didn't really go higher than 50%. I don't know what else it could be, suppose I'll live with it.

Thanks.