Mounting mechanism for fixing computer mainframe

A mounting mechanism for fixing a computer mainframe, comprising:

• a retaining base, comprising:
• a first plate, having an abutment face, a first end and a second end, at least one hanging tab being disposed on a position close to said first end of said first plate, said hanging tab being projected out of said abutment mean;
• a second plate, coupled to said second end of said first plate, said second plate being perpendicular to said first plate, said second plate being projected out of said abutment face, said second plate being disposed with a hole;
• a screw, disposed with a bolt, said bolt being coupled to said second plate movably, said hole of said second plate accepting said bolt;
• wherein said second end of said first plate is the lower end of said first plate and said at least one hanging tab is positioned above said second plate, or said second end of said first plate is the upper end of said first plate and said at least one hanging tab is positioned below said second plate;
• wherein said at least one hanging tab is adapted to extend in at least one hanging hole of a computer mainframe corresponding thereto, said bolt is adapted to extend out of said hole of said second plate to be engaged with a screw hole of said computer mainframe corresponding thereto.