Someone explain Modern CPU and GPU Bottlenecks?

[Revolution 11]

Concerning CPU-GPU bottlenecks, which one bottlenecks first for gaming? More specifically, which tier (price) of GPU is needed to bottleneck which CPU (price)? You can approach this from the other way if you want.

Requirements
Resolution is anywhere from 1280x720 at highest details to 1920x1200 at medium/high settings. No specific game in mind, pick a run-of-the-mill game. Not worried about loading times, but in-game performance. FPS should be 30-60+, I don't know. If there is a distinction, explain it.

If you explore other settings, I don't mind. I understand that AMD and Intel are different beasts in some aspects, so if you make a conclusion, please specify if it is in general or for a specific company. Same for ATI/Nvidia.

My question here is a general one and is not based on any hardware I will be buying recently. Forgive the newbie nature, please.

 

[Red Hawk]

It depends on the game, really. For the most part, strategy games like the Total War series or Starcraft bottleneck at the CPU before they bottleneck at the GPU. Physics-heavy games such as the Battlefield games or Red Faction tend to bottleneck at the CPU as well. Shooter games that focus more on texture detail and lighting effects more quickly bottleneck at the GPU.

Resolution affects just what bottlenecks, as well. If you're running at a low resolution, the GPU isn't being worked hard so it's up to the CPU to push the framerate. The higher the resolution the quicker the GPU bottleneck.

 

[GotNoRice]

Too many variables involved.

With games that are CPU limited, it could be limited in terms of the number of available cores, or the game might only use one or two cores and be limited by the IPC of the chip.

With games that are GPU limited, that might be because you actually don't have enough GPU power, or you might simply be running out of video memory at your preferred settings.

And in each case (though generally moreso with a GPU bottleneck) you can adjust individual settings to balance things out.

You can create a GPU bottleneck artificially in most situations just by forcing maximum AA - but is that really representative of a GPU bottleneck or a novice user?

And even within the same game and using the same settings, you might find performance to be great with 16 players but completely unplayable with 64 players.

You're going to be much better off trying to get the best CPU and Videocard combo for your particular circumstances than trying to work off some wildly inaccurate rule-of-thumb.

You could easily have the exact same hardware and experience a CPU bottleneck with one game and a GPU bottleneck with another.

 

[Revolution 11]

Well, I ask this question because I have heard many times that modern CPUs can handle most games and that many people get overly powerful CPUs but neglect their GPUs. But recently, more discussions of CPU bottlenecks are popping up so I am confused where more bottlenecks lie.

My core question was which tier of CPU should be paired with which tier of GPU (assuming a general mix of current games in all genres)?

A side question would be "How does storage devices affect these bottlenecks?". Do SSDs make a difference once the game is ready to go? I assume not since most games load into RAM.

 

[GotNoRice]

Well, I ask this question because I have heard many times that modern CPUs can handle most games and that many people get overly powerful CPUs but neglect their GPUs. But recently, more discussions of CPU bottlenecks are popping up so I am confused where more bottlenecks lie.

My core question was which tier of CPU should be paired with which tier of GPU (assuming a general mix of current games in all genres)?

A side question would be "How does storage devices affect these bottlenecks?". Do SSDs make a difference once the game is ready to go? I assume not since most games load into RAM.

Again there are just too many variables involved. A faster CPU is the safer upgrade. If you have a fast CPU and a slow GPU, chances are you can still achieve good performance in games, especially if you are willing to run at low settings. If you have a slow CPU and a fast GPU, you're going to get bad performance pretty much no matter what. The card won't be able to do anything if it's not being fed information fast enough.

When the Core2 Duo and Core2 Quad came out in 2006 they represented a massive leap in processor power. In addition, it was a long time before anything came out which offered a significant performance increase. This lead to the notion that anything of that generation or newer is "good enough" for games, which is still true to a large extent.

But we're finally seeing some good progress in the CPU area. Sandy Bridge CPUs represent a solid performance increase compared to older CPUs and bulldozer is right around the corner. It finally makes sense for people to upgrade.

When the Core2 series was new and games were still made with Pentium-4 era CPUs in mind, it was serious overkill. Now these CPUs have been out for 5 years and often represent the minimum CPU in the system requirements of modern games. Since games are finally making use of this extra processing power, it makes sense to start looking at something faster.

Games like BF3 are changing the way people think about CPU and GPU bottlenecks, in a large part due to the fact that the game is so much more demanding than most previous games.

For SSDs, again it depends on the game. For most First-Person-Shooters you probably won't see a huge benefit beyond loading time, but for an MMO like World of Warcraft there are clear benefits. Data is loaded on-the-fly as you move around the game world and you will often experience stuttering as you enter a crowded area if you are running the game off a mechanical drive because it can't handle loading so much data continuously.

 

[Denithor]

In the most general terms your CPU limits you at lower resolutions and your GPU limits you at higher resolutions (and/or higher detail settings, more AA, etc).

Basically at low resolutions your GPU isn't working that hard so it's more how many frames can your CPU push though. As your resolution/detail/AA is increased though, the GPU has to work harder and harder to keep up with the CPU and eventually becomes the limiting factor.

As mentioned above, with a crappy CPU you're not going to see good performance anywhere because it won't push the GPU at all, even in the low resolutions.

And the trend in needing more CPU power has been slowly growing over the last 3-4 years, some games need a quad to run smoothly while others can still run acceptably on a dual. But note that more people are upgrading to quads and noticing real differences even in games where a dual is nominally acceptable.