Dear Sir/Madam, When we use chimera to visualize PDB files with ~18,000 atoms (PDB ID 5FUU) even rotating the molecule is slow in chimera. The computer has 6GB RAM. Would upgrading RAM help or we need to get a graphics card installed? Graphics card capacity should be 2GB or higher? Could you please tell me the minimum computer configuration required by chimera to handle large PDB files? Also what is chimera's maximum limit for handling PDB files given a computer with very good configuration? Thank you. -- Shruti Khare Graduate Student Prof. Raghavan Varadarajan Lab Molecular Biophysics Unit Indian Institute of Science Bangalore +91-80-2293-2612 -- This message has been scanned for viruses and dangerous content by MailScanner, and is believed to be clean.