I have a Lenovo z51-70 laptop with 4gb of AMD r9 m375 graphics. The problem is when i play games when power cable is connected, the game runs smoothly (around 5 secs.) and then lags VERY BAD (20 secs) then again runs smoothly then again lags very bad. This cycle continues and when i remove power cable, the game constantly runs slow butnot as slow as when it lags during power connected. I also found that the GPU readings came in gaps (or pulses) when checked in GPU-Z (Image attached) and also the reading comes ONLY WHEN THE BAR COMES otherwise its blank stating 0 and -, the bar comes at intervals of around 10 secs. Please help me out with this. Will be happy to provide any more info if required.