Nvidia Optimus Allows 'Hot' Removal of GPU
Nvidia yanks GPU from live-running computer system.
Nvidia Optimus is a hardware and software technology that determines when applications require discrete graphics via software, supplying power to the GPU in response. This is done automatically, without the need to manually switch between integrated and discrete graphics.
For notebook users, this is a particularly useful technology as the additional power requirements of the GPU are only called upon only when needed. This should extend battery life, making all notebook users happy.
Nvidia has released a video showing Optimus in action that should help drive home how slick this new technology is. Rather than just put the GPU into an idle or low-power state, the system completely powers down the graphics part. With the GPU off, the system doesn't even mind if the dedicated graphics part is completely removed even while running.
"Few people ever get to see this demo because it requires a completely open notebook system – no chassis – just the motherboard, CPU, GPU, Hard drive, and monitor, so it is not exactly portable. This demo is really killer with engineering teams that design notebooks," said Matt Wuebbling, senior product manager of notebooks at Nvidia.
"They practically fall out of their chairs when they see it," he continued. "Why? Because with Optimus when the GPU is not needed it is completely powered off automatically and seamlessly WHILE the rest of the system is up and running – the power to the PCI Express bus, the frame buffer memory, the GPU - everything. This is in contrast to switching the GPU to a low-power state or to ‘idle’, which would still draw power."

depends how hot the chip gets if the temp variance is small it wouldn't matter too much.
Ha! Get it? Get it?! See, I...Oh forget it.
ROFLMAOWTIME
Although this is great when you would have 4 seperate GPU's and 3 of them aren't in use. I am not sure how stable it will be for overclockers though...
Some server boards can hot swap cpus/ram
Yeah, that's true, but only server mobos, not home mobos.