The Steam update released on September 9 is being called one of the most notable upgrades in recent memory, with a long list of new features aimed at improving the user experience, from the interface to performance and controller support. One standout addition is the ability to display CPU temperature while you play, though users will need to consider granting Steam special access to turn it on.
More detailed performance monitoring, but it requires kernel access
Back in July, Steam introduced in-game performance monitoring, but it could not show CPU temperature because of access restrictions. This update lets users turn on CPU temperature monitoring, provided they install a driver that runs in kernel mode (a kernel-mode driver).
Valve says this is entirely optional. Users only need to grant permission when they enable performance monitoring at its most detailed level, and they can also turn it off for individual games if they want.
Still, plenty of Windows users remain wary of software that operates at the kernel level, given the risk to security or system stability. On Linux, by contrast, showing CPU temperature does not require that kind of deep access.
Beyond the CPU, GPU usage readings on systems with Nvidia graphics cards have also been refined to display more accurately. Valve notes that the figures shown in Steam may be higher than, and differ from, those in the Windows Task Manager.
Steam improves its interface, library, and controller support
Besides performance monitoring, Steam has also received a major interface upgrade. Notably, DPI Scaling automatically adjusts text size to match the operating system's resolution, making text easier to read on high-resolution displays. Steam also adds a high-contrast mode, reduced motion, improved labels for users with disabilities, an expanded store layout, and a number of other small changes.
Users can now customize how games are sorted and displayed in their library through a new menu. You can change a game's cover art and display name more easily by right-clicking the game and choosing Properties > Customization. There you will find a custom name field at the bottom of the sub-panel.
Valve has also added support for Microsoft's GameInput API. This programming interface unifies how input is received from devices such as controllers, keyboards, and HID devices, and it simplifies support for a wide range of controllers for developers. The update also fixes a number of controller input bugs.
Alongside the official update, users of the Steam beta have had access to an even more extensive upgrade since July. Valve has not yet announced when it will reach the stable version, but says the main goal is to improve game discovery by reorganizing genres and categories on the main interface.

