How to sync two displays with two different resolution?

I want use one 4080 SUPER CARD with two DP outputs. One is set as 3840x2160x30fps, the other is 1920x1080x30fps. Then I turn on the G-SYNC mode. However, it seems that the two displays are not synchronized, as the videos out differ larger and larger.
If I set the two outputs with the same resolution like 1920x1080x30fps, the videos output synchronized as decades microseconds diff.
Then how can I make the videos with different resolution output synchronized?

Hi again, pls see my other posting to your similar question in a different forum. Answer there is still valid, here you are adding GSync, which is NOT a methode to sync 2 screens! (Quadro Sync, an extra HW add-in card, connected to the GPU(s), used to be called GSync, long time ago…).
GSync is a methode, to not make the screen run its fixed refresh rate, and the GPU need to send new images matching that refresh, but have the GPU send a new frame immediately when ready, and the screen refresh with the new frame immediately, so have a variable, GPU-driven refresh rate. This can only work well for a single screen, target is for lowest possible latency gaming… Running 2x screens in GSync mode the GPU will need to render 2 tasks alternativly, and refresh each screen alternating, when ready with the respective task, basically guaranteed to never refresh both screens at the same time ;-).

Based on your response, can I understand it this way?
If I want to achieve synchronous display of multiple different resolutions on a single graphics card with several output ports, I must use a professional graphics card, like * [NVIDIA RTX™ A6000];
if I want to synchronize across multiple graphics cards, then I need use a synchronization card (like Quadro Sync) to connect them?

not really! there basically is NO sync between different resolutions EVER! ONLY if 2 screens with different res run VERY EXACTLY the same say 60.001Hz refresh rate, there is a way to sync these 2, but today that needs a LOT of HW, IIRC 2x professional GPUs 4000 class and up, AND 2x Quadro sync cards… (we might be able to run this from lesser HW sometime in the future…)
Even 2x identical screens in extended desktop mode (so NOT unified as in Mosaic mode= single desktop), running exactly same resolution and refreshrate, to be kept in sync, need a QuadroSync card! Again, can’t at all sync a say HD screen running 59,999HZ and a say 4K screen, running 60,001Hz!
No sync between individual desktops, unless using a professional RTX 4000 class GPU, so RTX 4000+, RTX A4000+ or RTX 4000ada+ and a Quadro SyncII add-on card! (plus SW must be using NVSyncAPI)