A method for synchronizing video outputs of a plurality of independent video cards towards a single display frequency in a system comprising a plurality of image generator processors, the plurality of independent video cards, one of the image generator processors being a master image generator processor and at least another of the image generator processors being a slave image generator processor, and a reference signal generator adapted to generate a shared reference signal and comprising a predetermined target timer linked to the shared reference signal, wherein each of the plurality of image generator processors is adapted to drive at least one of the plurality of independent video cards and each of the plurality of independent video cards is adapted to support on-the-fly image refresh rate adaptation based on responsiveness from the corresponding image generator processor, the method comprising the steps of: - providing with the reference signal generator the shared reference signal for synchronizing, at the single display frequency, video outputs between the plurality of image generator processors; - at each one of the image generator processors, artificially affecting, in real-time, an image generation rendering speed during a next frame generation processing to trigger the on-the-fly image refresh rate adaptation by the one image generator processor's video card for proactively scheduling a refresh of an image corresponding to the next frame by the one image generator processor's video card, thereby aligning the refresh of the image with the shared reference signal while avoiding manipulation of memory registers of the one image generator processor's video card by the one image generator processor; the artificial affecting, in real-time, of the image generation rendering speed comprising scheduling the next frame generation processing by the predetermined target timer linked to the shared reference signal, wherein the video outputs comprises each of the images corresponding to the next frames from each one of the plurality of image generator processors; the method being characterized in that it further comprises: - providing to the reference signal generator by each of the at least one slave image generator processor a local delay as an indication of a time distance between a local slave reference signal and the shared reference signal; and - adjusting by the reference signal generator the shared reference signal based on the provided local delay. wherein each of the plurality of image generator processors is adapted to drive at least one of the plurality of independent video cards and each of the plurality of independent video cards is adapted to support on-the-fly image refresh rate adaptation based on responsiveness from the corresponding image generator processor, the method comprising the steps of: - providing with the reference signal generator the shared reference signal for synchronizing, at the single display frequency, video outputs between the plurality of image generator processors; - at each one of the image generator processors, artificially affecting, in real-time, an image generation rendering speed during a next frame generation processing to trigger the on-the-fly image refresh rate adaptation by the one image generator processor's video card for proactively scheduling a refresh of an image corresponding to the next frame by the one image generator processor's video card, thereby aligning the refresh of the image with the shared reference signal while avoiding manipulation of memory registers of the one image generator processor's video card by the one image generator processor; - providing with the reference signal generator the shared reference signal for synchronizing, at the single display frequency, video outputs between the plurality of image generator processors; - at each one of the image generator processors, artificially affecting, in real-time, an image generation rendering speed during a next frame generation processing to trigger the on-the-fly image refresh rate adaptation by the one image generator processor's video card for proactively scheduling a refresh of an image corresponding to the next frame by the one image generator processor's video card, thereby aligning the refresh of the image with the shared reference signal while avoiding manipulation of memory registers of the one image generator processor's video card by the one image generator processor; the artificial affecting, in real-time, of the image generation rendering speed comprising scheduling the next frame generation processing by the predetermined target timer linked to the shared reference signal, wherein the video outputs comprises each of the images corresponding to the next frames from each one of the plurality of image generator processors; the method being characterized in that it further comprises: - providing to the reference signal generator by each of the at least one slave image generator processor a local delay as an indication of a time distance between a local slave reference signal and the shared reference signal; and - adjusting by the reference signal generator the shared reference signal based on the provided local delay. - providing to the reference signal generator by each of the at least one slave image generator processor a local delay as an indication of a time distance between a local slave reference signal and the shared reference signal; and - adjusting by the reference signal generator the shared reference signal based on the provided local delay.