Random question about GPU workload

[Railgun]

If I play a really heavy game I might be getting around 40 FPS and my 390x is at full fan speed pushing out the frame rates as hard as it can. Then I can switch to a light game and get around 200 fps and my GPU isn't working nearly as hard and the fan speed is down quite a bit too. How does this work? What stops the GPU from working at full speed even in the lighter game but just giving my 699 FPS? I'm pretty sure it's not frame rate limiting within the game since my FPS will vary a little bit depending on whats going on.

[Samfisher]

If I play a really heavy game I might be getting around 40 FPS and my 390x is at full fan speed pushing out the frame rates as hard as it can. Then I can switch to a light game and get around 200 fps and my GPU isn't working nearly as hard and the fan speed is down quite a bit too. How does this work? What stops the GPU from working at full speed even in the lighter game but just giving my 699 FPS? I'm pretty sure it's not frame rate limiting within the game since my FPS will vary a little bit depending on whats going on.

CPU bottleneck.  If the GPU cannot render above x FPS and the usage is low, that means the CPU is holding it back.

[acturisme]

If you're really running an i7 then it's NOT cpu bottleneck.  It's GPU workload.  More FPS does not equal more GPU workload.  In fact more FPS generally means that the GPU is having an easy time rendering what is on screen.  It's when your FPS drops because you're running something like Metro 2033 or Crysis 3 at ultra settings at 1440 that give the GPU more work and therefore more heat.

[ShiroArikawa]

If you're really running an i7 then it's NOT cpu bottleneck. It's GPU workload. More FPS does not equal more GPU workload. In fact more FPS generally means that the GPU is having an easy time rendering what is on screen. It's when your FPS drops because you're running something like Metro 2033 or Crysis 3 at ultra settings at 1440 that give the GPU more work and therefore more heat.

he was asking why won't it push to 100% compared to 50% like 200 fps on 50 and 400fps on 100 why won't it is his question, mine too.

[App4that]

Higher the fps the easier the GPU has it, usually. Mine never reaches working temp until the fps drop below 60.