C#: Default implementation for == and != operators for objects

I'd like to know what is default implementation for equality operatort (== and !=)

Is it?

public static bool operator ==(object obj1, object obj2)
{
    return obj1.Equals(obj2);
}
public static bool operator !=(object obj1, object obj2)
{
    return !obj1.Equals(obj2);
}

So I only need to override Equals method or do I need to override euality operators as well ?