What makes a game CPU/GPU intensive?

[Johnny Who]

I was wondering if anybody here could answer what determines if a game is GPU or CPU intensive. Is it even actually a thing or just one of those things gamers simple keep repeating even if its not true?

 

Is it just a matter of, if a game isn't very graphically demanding than it will be the CPU that will be the problem if you experience low frames or is there more to it? Is it perhaps engine design, do certain game-engines maybe distribute workload differently?  Or is it perhaps the type of game that determines it, for example games that require complex AI are generally more CPU bound etc..

[rcmaehl]

Math. Plain and simple. Some specific types of math such as calculating vertices can be offloaded to a device specifically made for that kind of math, known as the GPU. Other kinds of math are loaded on the CPU instead.

[rcmaehl]

Stolen from Quora:

 

Basically a GPU is better at simple calculations on lots of data simultaneously. This is down to the way they are built. A GPU has a very simple control/logic unit:check out this diagram from nvidia showing the difference between CPUs and GPUs. Much more of the CPU is built of things to do complex control, cache handling, and other things and relatively less area for ALUs (arithmetic logic units.) In the end, GPUs can be incredibly fast when they're given very simple things to do in parallel, like a lot of linear algebra tasks. But they're incredibly slow when complex instructions are involved, especially things like switching statements (if-then-else type things), where CPUs fare much better.

GPUs need their instructions to be very close to "SIMD" -- Single Instruction Multiple Data - basically doing the same operation on lots of data. If it needs to do different instructions (like all the processes you see running in your OS) it would do that very poorly.

GPUs are extremely powerful for a fairly specific subset of problems. CPU's are much more flexible.

Specifically, GPU's do two things really well:

1. Floating-point operations (operations with decimal numbers instead of just integers), such as physics and graphics stuff
2. Operations that involve running the exact same code on a huge number of different data points at once. For example, calculating the light/shadow/color for all the millions of different pixels on the screen when rendering something. This is also known as "parallelism".

Another factor to consider about "General Computing" is that there's actually very few trivially parallelizable tasks outside the obvious (i.e. Graphics, Math Operations, Encoding, etc.) where GPUs dominate. Even if GPUs didn't have the branching / switching limitations that they did they would still be composed of (very very) many relatively "slow" cores.

[LogicalDrm]

It about what devs focus their optimization on. It is a thing, but you might not notice it with balanced system. However if you have lacked with CPU (mainly) and go to play CPU intensive/optimized game, you will note things aren't as smooth as they would. Fps might not be different, but other things will feel different.

 

Usually most games are GPU optimized/intensive. CSGO, Minecraft and Battlefield games after BF4 have been most known CPU optimized games.

[Guest]

Games where there is more logic used to calculate the state of things are more CPU intensive. However, games where there are lots of things to render and where shapes are more finely designed, are more GPU intensive. If they're GPU intensive and not CPU intensive, it probably means that more of the elements of the game are already set to happen and doesn't have to be determined on the spot. Civilization is an example of a CPU intensive game, though, because there are so many interacting parts that depend on each other and the CPU is tasked with managing all of those.

[_Hustler_One_]

It's all about what the developers does with the engine, if it will be CPU or GPU intensive based on some statistics.

This is one of the example

 

[Guest]

9 hours ago, _Hustler_One_ said:

It's all about what the developers does with the engine, if it will be CPU or GPU intensive based on some statistics.

This is one of the example

 

Hmmm I read that as "Multithreading in Wot?"