Graphics Switching

[Sureshot324]

Say you have a laptop with an Intel GPU on the CPU core (Sandy Bridge, Ivy Bridge) and also a discrete GPU. If you want to be able to switch between them, do you need Nvidia Optimus or AMD graphics switching or does this just make it more seemless? If you don't have that, do you need to reboot to switch or just restart the graphics driver, meaning a blank screen for a few seconds. Also, if you don't have Optimus/AMD graphics switching and you switch to the Intel GPU, does it completely shut off the discrete GPU, meaning good battery life?

 

[fralexandr]

you need the specific drivers provided by optimus or amd hybrid graphics and any other variant i.e. lucid logix (although their implementation is pretty bad last i checked).
optimus is the 3rd gen of nvidia hybrid power, the blank screen for a few seconds is what was done for nvidia's 2nd gen hybrid power drivers (most common example is probably the m11x r1), whereas the 1st gen required a complete reboot.

otherwise you'd have to toggle which gpu you want in the bios and most likely uninstall and install drivers to switch GPUs effectively.
if you uninstall the drivers, and set the bios to use intel integrated ONLY, it will not send power to the mobile pci-e/discrete card.

if special optimus/hybrid power drivers weren't required, there would likely be more desktops (other than the alienware x51) that actually use hybrid power.

there were issues with the 2nd gen hybrid power on the m11x r1 such that sometimes the nvidia gpu would not turn off thus increasing power consumption and causing the fan to be noisy at idle. one way to check if the discrete gpu was off was to check if it was listed in device manager. if it wasn't listed, it was off.

 

[Sunburn74]

You don't need optimus. Manual switching works fine (meaning you open a menu in the background and click the gpu you want active/ sometimes the only way to switch is to direct in your windows power plan which gpu to be active when plugged in vs battery and then you can control switching by just changing power plans that differ pretty much only in that regard). You should not have to reboot the entire PC. Only thing to note is that sometimes programs (particualarly background programs that have flash bars) will prevent switching between gpus so find those programs and turn them off.

I generally prefer manual switching because 90 percent of the time i want to be integrated graphics anyway and wouldn't want auto switching messing that up.