A schematic alone is sometimes not enough. If you find a Boardview file for the E93839, it will show:
Search for: "E93839 boardview" or "0JVT3 .cad". Use OpenBoardView (free software) to open these files. dell e93839 motherboard schematic link
Link type: Paid but high-quality scans.
Link type: Direct download (slow, 1 file per hour). A schematic alone is sometimes not enough
Alternative: Search for “OptiPlex 790 schematic” – the E93839 is the core board of that model. Search for: "E93839 boardview" or "0JVT3