fps_max

fps_max is a console variable available in all GoldSrc, Source, and Source 2 games. This is a ConVar where you can define your frame rate limit. It is recommended that you limit them to the refresh rate of your monitor, because any frame rate above that is wasted, and could cause the monitor to have screen tearing issues, causing the systems to make coil whine noises due to higher power draw. Furthermore, having more than around 1000+FPS in a Source games (or 100+ in GoldSrc) will cause timing-related issues (such as the game running faster than normal) and potentially causing the game to stutter (or cause the servers to teleport you back where you should be)^[1].

Note:Default: 300 FPS, 400FPS in CS:GO and Team Fortress 2 branch.

Note:Using value 0 disables FPS cap in Source/Source 2, while in GoldSrc it will make game run at 1 FPS

Note:On listen servers, going above 1000 FPS may cause pseudo-speedhacks, where time seems to have sped up. It should not happen on dedicated servers.^[confirm]

References

1. 3klikphilip -  1000 FPS in CS:GO????