It's not technically a ROM; you are running either a disc image or the actually PlayStation disc. Anyway, check that your screen is centered using the resolution that you use with ePSXe, simple as that. ePSXe usually knows perfectly well how to keep the game screen centered, provided that your monitor's settings aren't out of whack. Then again, it's very possible that there are games that don't center properly. What graphics plugin and settings are you using?