So the higher the resolution you game the less your CPU becomes a bottleneck?

[Helen Barber]

Don't most games only use 2 cores though?/

 

[smogsy]

Don't most games only use 2 cores though?/

2-6 cores depending on the game an AI complexity, its not just the cores its the frequency * IPC gains from 2500K to 5000s+ from intel.

5000 series is probably 30% faster clock for clock vs 2500k

 

[Aretak]

Don't most games only use 2 cores though?/

Most more demanding modern titles can use a lot more than that. Diminishing returns usually set in around the 6c/12t mark. A 10600K is essentially identical to a 10900K for gaming once both are overclocked, though there are some rare titles than can scale to eight cores and even beyond. Death Stranding scales up to and possibly beyond 32 threads.

 

[Mercutio]

The CPU runs the games engine. The games engine makes calls to whatever compatible graphics API's it's been coded to use (so DirectX, Vulkan, OpenGl, etc).

The CPU makes a draw call against whatever API. "Yo, GPU/DirectX12, take <this> scene and render it in your current graphics settings" (which is 1 "frame" of your "fps"). From this point ALL the work is on the GPU and is controlled by whatever graphics setting/res/etc you use.

So a FAST CPU can make MANY of these API calls, easily. It's a(n almost) static workload on the games engine. A SLOW CPU starts to struggle making these API calls fast enough.

A FAST GPU can handle these calls with high levels of detail/resolution easily. A SLOW GPU struggles with higher quality graphics settings as it has more work to do.

So (to make the best use of CPU and GPU)....

FAST CPU and FAST GPU = Many frames per second at high detail. E.G 5800X + 3090 will (generally) give HIGH frame rate 4K and should still be pushing 100/120hz @ 4k.
FAST CPU and SLOW GPU = Many frames per second at low detail. E.G 5800X + 1070ti will (generally) give MANY frames of 1080p quickly and is good for high hz 1080p
SLOW CPU and FAST GPU = Lower frame rate but the graphics card can handle way more detail per frame. E.G 1600X + 3090 will give.... "ok" frames at high detail e.g. 4K+max detail 60hz
SLOW CPU and SLOW GPU = Lower frame rate and lower detail. E.G 1600X + 1070ti will give moderate frame @ moderate detail, probably decent 1440p


All this is just relative. I'm not suggesting a 1600X + 1070ti can't do awesome work. Just VS alternatives and to give an idea.


If the GPU is high performance, it's able to deal with "easier" draw calls quickly so you get a CPU that's maxed out trying to push work (draw calls) to the GPU that it completes with ease and is constantly sat waiting for CPU. You'll see GPU usage is <100% (usually 50-80) and CPU is maxed out. At this point, you should improve CPU or increase detail/res.

If the CPU is high performance, it's able to push MANY draw calls to the GPU that the GPU then needs to handle quickly (which becomes frame rate/fps). If it's not able to, due to higher visual quality settings being configured, you see the GPU maxed out trying to render frames and the CPU is <100% used. At the point, you should improve GPU or reduce detail/res.

In pretty much all cases, MSI afterburner can be set up to show you the GPU usage and the usage (and usage per core) of CPU. Use the last 2 lines above to tune your rig to make the most of your available kit.

Take this understanding with Zefans suggestion about scaling. MSI afterburner will show current levels... check power/usage of current CPU/GPU, compare with CPU/GPU you want to move to. You should be able to work out if either will be restricted by the other.

 

[JamesPliskin]

@Mercutio Very informative, thank you.

 

[gpuerrilla]

Look up.

He didnt..bother

 

[PrincessFrosty]

The CPU runs the games engine. The games engine makes calls to whatever compatible graphics API's it's been coded to use (so DirectX, Vulkan, OpenGl, etc).

The CPU makes a draw call against whatever API. "Yo, GPU/DirectX12, take <this> scene and render it in your current graphics settings" (which is 1 "frame" of your "fps"). From this point ALL the work is on the GPU and is controlled by whatever graphics setting/res/etc you use.

A good in depth post. It's worth also adding that this primarily discusses the rendering portion of the game engine. However to draw a new frame the video card needs to have an updated world state, the new positions of objects based on player movement, physics and decisions by AI and all that good stuff. Typically in games that are CPU bottlenecked the CPU is spending more of its time updating the game state of the engine itself and not making draw calls.

This is why sim games tend to be the games that run into CPU bottlenecks first, it's less about the draw calls and more because real time simulation can be computationally expensive and the CPU has to chew through all of that stuff before it can update the game state and only once all that is done can you make draw calls for the next frame to be drawn.

 

[gpuerrilla]

A good in depth post. It's worth also adding that this primarily discusses the rendering portion of the game engine. However to draw a new frame the video card needs to have an updated world state, the new positions of objects based on player movement, physics and decisions by AI and all that good stuff. Typically in games that are CPU bottlenecked the CPU is spending more of its time updating the game state of the engine itself and not making draw calls.

This is why sim games tend to be the games that run into CPU bottlenecks first, it's less about the draw calls and more because real time simulation can be computationally expensive and the CPU has to chew through all of that stuff before it can update the game state and only once all that is done can you make draw calls for the next frame to be drawn.

Good point, I forgot about that tbh when people talk about GPU's. Reminds me of the 2005 open PVP server crashes when mass players rocked up for action and the CPU's and servers would be going nuts trying to keep up lol.

 

[Helen Barber]

Well I only plan on getting a 60hz monitor so I think I should be fine for the games I play.

I don't need 120fps as my monitor won't support it and I don't play FPS games.

So I'm sure 6900xt @4k and 2700k @4.9ghz at 60fps will be ok

 

[HangTime]

My gut feeling is 6900xt will be overkill a bit, I doubt it will carry much benefit over 6800xt on a 10 year old cpu. A 6900xt only really makes sense if you were wanting to push 4k at over 60fps, which you aren't.

 

[gpuerrilla]

Regular 6800 should be ample.

 

[Kaapstad]

Well I only plan on getting a 60hz monitor so I think I should be fine for the games I play.

I don't need 120fps as my monitor won't support it and I don't play FPS games.

So I'm sure 6900xt @4k and 2700k @4.9ghz at 60fps will be ok

You can use almost any CPU @2160p if you are using a 60hz monitor.

Being limited to 60fps means you can max the settings in games which also avoids CPU bottlenecks.

Going forward though you should consider upgrading your CPU as modern games can use more than 4 cores and older CPUs also suffer more from dips in fps.

 

[Helton Leal]

Bottomline to simplify, CPU is required to prepare the pipeline to draw each frame, the less frames you draw, the less CPU your game needs to trigger, so basically, higher resolution = busier GPU, which means less FPS, which means less CPU being triggered to prepare the drawing pipeline between each frame