1. A system for diagnosing and testing computers, comprising: a graphical user interface tier, offering users a graphical user interface to show the progress and results of testing hardware components and generating diagnosis configuration files in accordance with a selected computer hardware component as needed; a test logic tier, the test logic tier comprising a test items module, the test items module comprising a plurality of sub-modules which run to test different computer hardware components respectively; and an invoking logic tier, for invoking the sub-modules of the test logic tier in accordance with the diagnosis configuration files generated by the graphical user interface tier; and the test logic tier further comprises a parser module, a progress module, a common module, and a test arithmetic module, which can be invoked by each of the plurality of sub-modules; wherein each of the plurality of sub-modules is a blank logic module which occupies virtual memory before invoking the parser module, the progress module, the common module, and the test arithmetic module.