crash – Ubuntu 18.04 repeatedly crashes on HP laptop with AMD Ryzen 3550H

So I bought a new laptop with an AMD Ryzen 5 3550H CPU, with Nvdia graphics, and have dual booted Ubuntu 18.04 onto it. The problem I face is that the system keeps on crashing after some time, every time. I have been trying to find what crashes the system, using htop. I see that even though the usage of each cpu core is less than 100%, with an average around 30%, the system still crashes. I’m no tech pro, and so dont kno what to do apart from checking htop, so it would be great if someone could help me out. Happy to provide any files