A computer system and a monitoring device for a computer system are disclosed. The computer system includes a plurality of electronic modules, a memory module and an embedded controller. The embedded controller is coupled to the electronic modules and the memory module, respectively. The embedded controller collects information of the electronic modules and generates the system information about the electronic modules. The embedded controller selectively writes the system information into the memory module. The system information in the memory module can be provided to the user or the maintenance engineer for system analysis. Besides, the computer system may utilize an application program to monitor the system information, so as to achieve the error prevention and alert function.