Virus-miner who can't catch.

Good afternoon, faced with the overheating of the CPU (70c) idle. I thought that the problem is in the paste/dust, replaced/removed. The temperature remained the same. When you call the DZ noticed that at startup shows 100% CPU usage, which is then dramatically reduced. Went to HWMonitor, where he noticed that all the cores busy almost 100%, but it is necessary to run the DMZ, as the load begins to decline sharply and the CPU temperature to fall. In games the laptop acting weird, then it all goes very smoothly, it starts drop in FPS. All of his symptoms on the computer stuck virus-miner, which I tried to get Avast, AVG, and Сureit, they showed a clean PC. What can you recommend?