My laptop is suddenly freezing

Hi, I have samsung sens sf310 laptop for almost like 5 years. I had no issues untill I bought it. But, from 2 weeks before it started suddenly freezing. Happened several times. Then, i thought it's hard drive problem. So, I replaced my hard drive with an ssd and install fresh windows 10 pro. Used it for two days intensively. Then, again suddenly it started freezing. now, i don't really know what exactly happened to it. It runs perfectly smooth when everything is okay, no lag nothing at all. Then, it suddenly hangs and no response. Only pressing power button for few seconds shut it down and after that it runs again okay. No overheating issues so far I can feel in normal condition with my hand. Please let me know if someone knows what actually got wrong. It came with 3GB ram built in, I upgraded to 6GB before may be 2.5 years. Is there any possibility that ram could go wrong? N:B I casually play league of legends and asphalt 8. Other than that just normal tasks like browsing through chrome(64bit) and thats all. Any suggestion would be greatly appreciated. Thanks :(