If I read correctly there seem be two problems.
1. Sempron 3400, 1.8GHz running at 800MHz.
2. Correct VGA driver does not take/install for the Xpress1100.
The 1st case should be unrelated to the VGA driver issue. It appears as Cool'n Quiet is enabled and clocks down to 800MHz. This is controlled through BIOS and OS, Power Options.
Overclocking on boards with onboard VGA is sensitive, would not try to go to far.
Use Ccleaner and driver cleaner after the vga driver uninstall, prior to loading the new Chipset driver
and VGA driver.
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