I face the same problem with windows10. I tried to install the x86 driver from version 1.6.8 of the IDE but the system claims it cannot be used.I was able to create a COM port and change it to COM1 as required by the IDE but it cannot coonect to the arduino on the USB cable.
-real Arduino or bought on eBay/China/AliExpress/Amazon?
-Do you really have a x86 system :o
@effiko, please do not hijack. Thread split.
The ide doesn't require it to be COM1 - you can choose port from tools -> port
If it's a clone it may have a CH340G serial adapter ( check marking on chip next to usb connector) - this uses a different driver, Google will find it.