There is no 3D graphical effect in PS4 OS... PS3 didn't used GPU too and the UI are similar.

Xbone 10% reserve is for Kinect and  OS... Kinect processing uses a good amount of GPU.

Is the PS4 OS graphical effects rendered in the CPU? If not then even if the effects are 2D some (small amount) of the GPU must be reserved for it.

What OS graphical effects? The PS3 OS graphical effects are made by GPU? No.

Until the Metro UI the Windows didn't used GPU for graphical effects... just after it they stated to use GPU... the Windows XP didn't use any GPU for it and it had more graphical effects than PS4 OS.

It was pretty much just fanboy guessing. Lots of Sony guys said it was much smaller than this, but lots of Microsoft/wii u guys said it was like this or larger. 

?

Aero on Windows 7 used the GPU to render effects (I am also sure Vista used GPU rendering but I am not certain on that)

The PS4 has quite a few visual effects, I do not know if they are rendered in the cpu or gpu.

Ohhhhhh I forget the Aero lol... it was made for Vista and used a lot of GPU... on 7 they fixed and it used way less GPU.

That's my point I don't see these visual effects that needs GPU use... what I see is transictions like Windows XP had... I can be wrong but I don't think PS4 OS uses GPU like PS3 OS didn't used too (the transictions are similar).

To give some support for your theory... the Cell on PS3 could render complex graphics too... so they didn't need GPU at all.

Edit - Just to be clear... the 10% that MS reserves is not for OS graphical effects at all...

MS:  "Xbox One has a conservative 10 per cent time-sliced reservation on the GPU for system processing. This is used both for the GPGPU processing for Kinect and for the rendering of concurrent system content such as snap mode," 

Mort: "Gpu for that certain system had 10% reserved. 8% video. 2% voice. Voice will remain. That video 8% will be up to devs. As it should be."

Xbone uses for Snap and Kinect Audio/Video... MS is using the GPGPU from GPU to Kinect and Snap graphical effects... PS4 don't have any.

Another possibility is that Sony reserved some of the GPU so it would be there in case they decided later to add anything that uses the GPU to the OS?

It would not suprise me either way about the effects being rendered in the cpu or the gpu. The PS4 CPU is more underpowered than the GPU so I am not sure what they have done.

Read every single page, the lowest prediction I found was 1gb reserved for OS.

please dont waste my time like that.

I agree... could be both but nowhere close to the 10% MS is using because PS4 don't have Snap or Kinect... the PS Eye just works in game if the Devs choose to implement and use the game resources to use it.

http://www.neoseeker.com/news/6840-latest-firmware-update-for-psp-unlocks-a-higher-clock-speed/

Here is an instance. While not confirmed, I would guess hardware manufacturers can unlock this only for their first party studios, to make their exclusives look beter. I dont know much of anything about computer engineering but this isnt the only case. As the gen goes on the os/oses should drastically reduce freeing up ram as well.