Recently, I have been experiencing 'lag' when playing CSGO and most games in general. My motherboard only supports ethernet and I do not own a network/Wi-Fi card. It happens rather on and off, but not like normal short term 'lag spikes', it lasts maybe an hour or so, and only makes an impact on gaming, nothing else. Here is a screenshot I got from speedtest:
http://i.imgur.com/XtxIQMd.png
http://i.imgur.com/XtxIQMd.png