Riot please, I need help

So about a week ago I started encountering a problem. Every so often I would just not be able to move and nothing would be happening on my screen, the avatars would move but nothing else, no damage would be done or anything. It would say my ping spiked and my fps would drop to almost none, afterwards it would all happen in about 1 second. Its not my card as I bought a new one. (Gforce GT 730) and I had a worse card before and didn't run into this problem with the older card. someone told me it might be my Modem card but I don't see how that could affect anything this badly. anyways I just want some help from anyone as to what could be causing this.