What is a MUX Switch and what is it good for? - TUXEDO Computers

TUXEDO notebooks with a dedicated graphics card alongside the iGPU in the CPU are very popular in the gaming community. In this article, we explain what MUX switches in some of these devices are all about.

MUX switch? Never heard of it?

Don't worry, you're not alone. MUX switches, which are actually called multiplexer switches, are not necessarily part of everyday life, but they are highly interesting for gamers, for example. Many TUXEDO notebooks have a second graphics chip as standard, or offer such a second graphics option in the configuration in our store. We then speak of a GPU integrated into the CPU (iGPU) and a separate GPU (dGPU). The dGPU is more powerful than the iGPU, but also consumes much more power.

NVIDIA Optimus

So, to balance battery life and graphics performance to your liking, these laptops often used for gaming switch spontaneously between iGPU and dGPU. In the case of the dedicated NVIDIA GPUs offered by TUXEDO so far, this is handled on the hardware level by Optimus, a technology also known as MSHybrid, which only switches on the dGPU when needed, but otherwise uses the power-saving iGPU.

However, there is a caveat. This solution is not optimal for gamers because when Optimus switches to the dGPU for a graphically intensive task, the content rendered by the dGPU is routed through the iGPU. In doing so, the iGPU becomes a bottleneck, which can lead to increased latency. For other graphics-intensive activities, such as video or 3D rendering, you can calmly use Optimus because the power-saving iGPU is used again when the program is closed without a system restart. 

However, the output of the content rendered by the dGPU via the iGPU does not apply to TUXEDO notebooks like the Stellaris 15 and 17 with AMD CPU and soon the new Polaris 15 and other new devices where the dGPU is directly wired to the HDMI and DisplayPort output (also DisplayPort over USB-C). 

MUX should fix it

This is where the MUX switch literally comes into play, as it allows gamers to bypass the iGPU bottleneck. In a nutshell, a MUX switch allows you to disable the integrated graphics in your gaming notebook to increase performance while gaming. It's a hardware switch on the laptop's motherboard that modifies the connection between the dGPU and the notebook's display as if the connection was hardwired to keep the iGPU out. External displays are independently and unalterably connected to iGPU or dGPU. NVIDIA Optimus is then disabled.

The user can set the desired behavior in the UEFI settings under Advanced | Switchable Graphics. Depending on the game at hand, this allows an average of 10% higher frame rates. However, the power consumption also increases, and not only during gaming, because the more power-hungry graphics card is active non-stop even when the system has nothing to do. One of the positive aspects is that NVIDIA G-Sync can be used, provided the display supports this technology. At TUXEDO, the current models of the Stellaris and Polaris as well as the Gemini series like the Gemini 17are equipped with a MUX Switch.

Options without MUX switch

Without a MUX switch, you can only bypass Optimus by connecting an external monitor to your notebook. In this case, the display output must be connected directly to the discrete graphics and not to the integrated graphics from Intel or AMD. A simplified method that allows you to flip the MUX switch without visiting the BIOS/UEFI is NVIDIA's Advanced Optimus. For Linux, Advanced Optimus is still in the implementation phase. Here, however, the on-demand mode works as a counterpart to Optimus and can be switched via command line or GUI and also works with external displays, provided the dGPU is wired directly.