A little tool to check if your GPU is operating at max link width and PCIe generation. Version that acceses PCIe config space directly.
Apparently some platforms have problem negotiating full PCIe 4.0 link with certain Nvidia RTX4090 cards and fall back to 1.1 speeds. As a result GPU performance is non existent. This happens at random on some boots.
I've got tired of having to remember to launch something like GPU-Z each time to check. So I wrote a simple tool that will display a system tray toast when GPU link is slower than card capability. It was also a nice into to how PCI Express standard works under the hood and how to access raw config space data under modern Windows (8.1 and up).
Put the .exe in any known folder.
Create new task in Windows Task Scheduler with trigger At logon: Any user. Select Start a program as an action pointing to the .exe and passing -q as a parameter.
In General tab tick Run with highest privileges
To test you may omit -q parameter and manualy launch task from Task Scheduler. Console window with GPU link parameter should appear, same as when you launch .exe directly.