According to a post over at Nvidia Geforce forums, spotted by Techpowerup.com, Nvidia has disabled the overclocking feature on GTX 900M mobile GPUs with the latest Geforce 347.29 drivers, although the GPUs were previously overclockable. Quite a few angry users have reported the bug over at Geforce forum only to get an explanation that the overclocking feature on the GTX 900M series GPUs was only enabled by accident.
According to Manuel G, a member of Nvidia's customer care team, "Geforce notebooks were not designed to support overclocking. Overclocking is by no means a trivial feature, and depends on thoughtful design of thermal, electrical, and other considerations. By overclocking a notebook, a user risks serious damage to the system that could result in non-functional systems, reduced notebook life, or many other effects.”
While some overclocking voids the warranty, it appears that Nvidia did not want to left that choice for buyers of notebooks with Geforce GTX 900M GPUs, something that did not go well with some users, which argue that they should be able to use the hardware as they want, even if it means voiding the warranty, which we tend to agree.
On the other hand, Nvidia probably wants to make sure that the overclocked GTX 900M GPU is not the one to kill the notebook as it would get Nvidia in hot water with many manufacturers.