This is just a guess on my experience. It might be because Cachyos has chosen to install the Nvidia 555 driver…this works for a lot of hardware setups (including my laptop), but for my more modern desktop, it produces a black screen because the 555 driver doesn’t work with my monitor (I have a NVIDIA 3090 GPU and a ultra HD monitor). You might try suggestion at NVIDIA 555 is live and some Information's to revert to the 550 driver.