Try this way for windows 8.1 if you have problems
This is the second one that i installed. I have been using usb to serial converters, and wanted to install these on my two computers that i use for digital ham radiio. Item is exactly as described, with full profile attached, and low profile in box. I run windows 8.1. I always make a restore point before installing any hardware or software, just a thought. Install it, start the computer, go to device manager, and you will see a yellow triangle with an exclamation point in it, no problem. Insert the cd, right click on the device in device manager, select update driver, choose select from my computer, select the cd drive, for example e:\, and let windows install the drivers. Refresh your screen, you will still see the yellow triangle, no problem, check your com ports in device manager and one will be installed, right click on the yellow triangle for the device again, and follow the same procedure. Refresh your screen, yellow triangle is gone, check com ports in device manager and you will have two brand new serial com ports. I tried it the way the instructions said, and it did not work. I did it the second time as described above, and no problems, just remember to do it twice. This is the way it worked in a dell inspiron tower in a pci e16 port with windows 8.1, i do not know nor speak for any other computer or os. Hope this helps someone.