Yesterday, my brother who was running the Windows 8.1 Preview on his Asus S400CA Ultrabook ran into a big NTFS partition corruption problem that made it impossible to recover via the Windows 8.1 refresh utility. Given the situation my brother decided it was best to return to Windows 8, I had to install Windows 8 on his PC using an external DVD drive with a full retail Windows 8 x64 installer that I had previously purchase. The computer never asked me for a product key which I read is normal in Windows 8 PC which now have these embedded into the motherboard. So far a smooth installation, however it got tricky in the part of driver installations. Before deleting the computer I went to the Asus website and did my best to find the drivers specific to my brother's computer and downloaded the essential drivers, chipset, intel graphics, audio, bluetooth, Wireless LAN, LAN, and Asus trackpad and installed them. I used the Device Manager to check out which drivers were installed and which were not. I was able to get most of the drivers correctly installed however, the Device Manager is saying I am missing the 'PCI Data Acquisition and Signal Processing Controller' driver. Unfortunately I have going to Asus website to see if I can find the driver however, I am unable to do so at this time.