Driver problems for Aspire E5-521  

Model: Aspire E5-521
BIOS (UEFI) Version (currently set to Legacy): ATI VGA VER015.042.000.002.000000
Original Operating System: Windows 8.1
New Operating System: Windows 7 64-bit
Type of Issue: Could not locate Chipset Driver, PCI Device, PCI Encryption/Decryption Controller, SM Bus Controller, and USB Controller.

Hi guys! I bought this unit last wk, and it was a bit sluggish for me. Thinking that it might be the OS, I changed it to Windows 7 64-bit, which is currently installed now. I have been having problems finding drivers for this. I have used the drivers found here -- Acer | Download Drivers and Manuals | Acer Official Site but I noticed that "Operating System" says "Windows 8.1 64-bit".

Still, I used those drivers listed there. However, after installing those drivers, I still see yellow-exclamation marks on the following:
- PCI Device
- PCI Encryption/Decryption Controller
- SM Bus Controller, and
- Universal Serial Bus Controller

I also noticed that after installing the drivers from Acer | Download Drivers and Manuals | Acer Official Site, my machine kind of became sluggish I really hope you could help me on this as I have been struggling since yesterday Thank you all in advance.

Hi! Sadly, I've already done that. I've also pasted the DEV and VEN IDs here -- PCI Vendor and Device Lists, but it did not yield any results when I clicked on the link/page that follows after that. As of now, the only ones that are left without drivers are PCI Encryption/Decryption Controller and Universal Serial Bus Controller. I left them as they are since I don't see any problem leaving them without drivers (I assume). Thank you for the time, and I think I shall be marking this as solved for now. :)

@ m1ndf33d
i am going to format my unit and install win 7 ultimate, do you mind to share with me the win 7 drivers?