user38206: I have downloaded and used Arduino IDE v1.8.4 from official site (needs no install) for windows10, and connected my random board with a ch340, but it's LED is only blinking and I can't select the port (ie. it's grayed). 
I did test all USB ports and restarted my laptop but that didn't work!  
I tried to install 1.6.9 IDE that I had before, but again the port option is unselectable!
This is my board: 
http://uupload.ir/files/xgv_uno.jpg

user38174: Simplest possible thing would be that you do not have CH340g driver installed and you should try installing it first; These boards use CH340 for usb to serial and they need the driver to be installed; Please give it a try by getting the driver from the following link http://www.wch.cn/download/CH341SER_EXE.html or any other reliable source if there is any problem with the link;
If the board is not recognized even after that, it could be a bad USB port or a bad USB cable or even a board with the CH340 chip dead;

38206: <p>I have downloaded and used Arduino IDE v1.8.4 from official site (needs no install) for windows10, and connected my random board with a ch340, but it's LED is only blinking and I can't select the port (ie. it's grayed). </p>

<p>I did test all USB ports and restarted my laptop but that didn't work!  </p>

<p>I tried to install 1.6.9 IDE that I had before, but again the port option is unselectable!</p>

<p>This is my board: 
<a href="http://uupload.ir/files/xgv_uno.jpg" rel="nofollow noreferrer">http://uupload.ir/files/xgv_uno.jpg</a></p>
 38174: <p>Simplest possible thing would be that you do not have CH340g driver installed and you should try installing it first; These boards use CH340 for usb to serial and they need the driver to be installed; Please give it a try by getting the driver from the following link <a href="http://www.wch.cn/download/CH341SER_EXE.html" rel="nofollow noreferrer">http://www.wch.cn/download/CH341SER_EXE.html</a> or any other reliable source if there is any problem with the link;</p>

<p>If the board is not recognized even after that, it could be a bad USB port or a bad USB cable or even a board with the CH340 chip dead;</p>
