A device and method for performing switchover operations and data comparisons in a computer system having at least two execution units. The execution units process data with prescribed clocks separately, wherein a changeover switch being provided which switches between at least two operating modes, a first operating mode corresponding to a comparison mode, and a second operating mode corresponding to a performance mode, in addition, a comparator being provided which is activated in the comparison mode, characterized in that a synchronization device is provided to distribute clock information to desired data according to the execution units, and at least the comparer will pay attention to the clock information to corresponding data.