What does Fn-F7 do exactly?

I've been wondering about this since the day my R4 arrived. What's the purpose of Fn-F7 (I/D GFX)? It doesn't seem to do anything useful to me.

Pressing the key and switching to the IGP doesn't even seem to power off the dedicated GPU, it still reads the same temperature idle (59c through nvinspector) just like when it's set to dedicated GPU mode only. There's obviously still power being routed to the GPU for it to produce 59c idle temp. Why can't it just completely shut off the dedicated card in times it's not needed and toggle it on when it is?

What's the purpose of a feature like this if it just keeps two GPUs on?

 

if you have 3D screen.. nvidia gpu is on 24/7.. igpu is disabled completely.. thus fn+f7 serves no purpose..

if you have non-3D nvidia gpu.. optimus automatically does all the gpu switching based on your whitelisted apps.. again fn+f7 serves no purpose..

if you have a amd radeon gpu.. fn+f7 might do something..

 

I had an R4 with an Nvidia GTX 680m / Intel HD 4000 and the regular 1080p screen. Hitting Fn+F7 would prompt me to switch the GPU I was using after a computer restart. However, it was never really clear what I was switching to or from, and the system wasn't always very transparent about letting me know which state I was in.

Sometimes I would end up in a state where both GPUs were active, and Optimus would switch between the two based on my settings in the control panel (which I assume is the default). Other times, it would completely disable my 680m, OR my HD 4000, so that the system was only using one or the other. No Optimus, no dynamic GPU switching, no nothing. Couldn't change GPU without restarting the computer again.

So my computer would constantly be toggled between three different states (1. Optimus, 2. GTX 680m, 3. HD 4000), and it wasn't ever made completely obvious which one I would be switching to when I hit that button. This threw me all out of whack for a very long time, and eventually I decided I'd just restart the damn thing over and over again until it was JUST the 680m, and completely stopped bothering with the switcher from then on.

 

Speaking from a 7970m perspective, one state is iGPU disabled (dGPU only aka discrete) and in this mode you will not see the iGPU in your Device Manager nor be able to get any readings on it from software, it's OFF or essentially uninstalled. The 2nd state is dual GPUs enabled and you're supposed to decide within the CCC software which apps get what GPU (e.g. browser assigned iGPU and Crysis assigned dGPU). Because the 2nd state allows for either GPU, they both have to effectively be ON. Once you get some apps listed with the GPU you want it to use, you'll find more often that the dGPU to be in a sorta sleep state where clocks won't show up on software, but eventually something tends to wake it up in my experience.

It's not perfect in my experience, but the absolute true reason for Fn+F7 is AW seen the issue with AMDs graphic switching and nipped it in the bud for us by allowing us to select a dedicated only (dGPU) when we game. If you want to know what happened to those that didn't buy AW 7970m, research the Clevo/AMD low gpu usage problems.

 

I my experience with Windows 7 Fn+F7 would disable HD4000. Intel GPU then would not appear in a device manager after computer restarts. Next time you press the combination it would turn Intel card back on and Optimus kicks in. I never had a state where my GTX680m would be disabled.

Now in Windows 8 this is another story - Fn+F7 does not work. If I try to disable HD4000, laptop would restart again and Intel would be enabled. This happens because of Secure boot (+fast boot) settings in BIOS, which lets my system cold boot in around 8 seconds. I did not notice any performance degradation with Intel card enabled, so this does not really bother me too much.