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Wow a Win XP retro build, you will need to eventually post some photo links
OK, what Nvidia driver are you trying to use? (you may need an older driver, from back in the day of XP & Not one of the newer drivers)
Nvidia ended support for Win 7 & 8.1 systems back in 2021 ...... version 473.81, back around August 2022, was released as a security patch for W7 & 8 ..... so, I'm not sure what driver actually will work in Win XP
What type of cable (& adapters) you are using to connect the GPU to the monitor?
Is Fast Boot off in MB, BIOS settings (if that is even an option)?
Might want to take a look at this --->
The EVGA GeForce 600/500/400/200/8/9 Series Master Sticky List