There are many online antivirus software available for PC 2014.Personally, I want to suggest AVG, Optimodefender and Avast antivirus software. It doesn't use much memory of the computer. Long scan time, but the results remain accurate.
Avast is good, highly rated, but I was disappointed with their sneakiness with popup indicating there is an update, which installs the paid version (trial). I wasn't impressed with that. I changed to Avira which is rated almost as highly.