Pay attention: a few chats waiting in tray reserve 1GB VRAM for themselves.

If an application uses a Web-based interface and "hardware acceleration", it constructs its frame in VRAM and sometimes keeps it reserved even if the app is minimised. On my Linux machine, Discord is the worst offender, reserving 450 MB VRAM. Steam takes 200 MB, Telegram 150 MB, and a few other apps top it up to 1 GB+. If you are really squeezing something into VRAM, make sure to either close those apps or turn off "hardware accelera