You use a large monitor, what does my forum look like on your screen picking full-width style. Will you post a screen-shot of it?
My monitor is 24 inches wide, your forum looks huge in it but so does WoltLab's. I can post a screen shot of what I'm seeing on your forum but I don't think it will do you any good.
I don't think it's necessary to have forums displayed at such a large size if images or video isn't the main content.