Mining is an intensive activity that puts a lot of load onto your system resources. If it is a GPU miner that is running in the background, youu2019ll notice a substantial decrease in performance if you run any GPU intensive software, for instance games. On the other hand, if it is a CPU only miner, your PC should be noticeably slowed overall. If either of this happens, it can be due to a million different reasons but definitely a cryptocurrency miner running in the background is one of them. if the malware is intelligent and can utilize system resources in a way that it only uses the available free resources, you might never know the miner is actually running on your system. This is even harder to spot.One of the first steps you should do is remove any program that isnu2019t important for the system and the ones that you havenu2019t installed. Go to the task manager and see the process that are currently running and the ones that you do not recognize, find out more information about it on the internet. Also, most anti malware and anti virus suits cover mining malware so you just need to get one (even the free ones do the job) and run a thorough scan on your PC.