Obtain the opengl32.dll and its associated configuration file from a trusted source.
Most OpenGL hacks for CS 1.6 are distributed as a replacement file.
These hacks are generally not VAC (Valve Anti-Cheat) safe . Using them on Steam servers will likely result in a permanent ban.
Modifying core DLL files can cause the game to crash or force it into "software mode" if your graphics card drivers are incompatible with the modified library. Legitimate Performance Alternatives