You didn't need to start a new topic, just ask for more info in your other one. Anyway, yes it seems that NVidia's drivers seem to leave some nasties behind that can cause stability issues or slower performance when swapping to a new card. Most of the time there's no probblem.
It happens, but it's rare you need a OS reinstall for stability issues, but doing so can make sure you don't lose even a tad performance. 3dmark competing fanatics would want a new OS install for sure.
not to sweat though. As was said properly uninstalling your old NV drivers is a smart move. Remove them from within add/remove programs, and also using a driver removal tool such as driver cleaner, detonator destroyer, detonator RIP. Doing this your should be just fine. And by the way, swapping from a NV to a NV can also cause issues, so don't use this as a reason to stick to NV for good.
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