A user reports that a printer is leaving streaks on printed pages.

This is because the fuser is the part of the printer that heats and melts the toner onto the paper. If the fuser is defective or dirty, it can cause streaks or smudges on printed pages. The system board and the memory are not related to the quality of the print output. The paper tray may cause paper jams or misfeeds, but not streaks on the paper.