Need more info such as:
make/model of motherboard
make/model of power supply
make/model of RAM
make/model of SSD and Hard Drive
*Most computers made by builders and sold on ebay cut corners in quality, since most people buying off ebay are looking for cheap, and cheap usually means lower quality components or buying other peoples problems. Im assuming that its not a quality build. Maybe the parts listing will prove otherwise. You could have a combination of a cheap unstable power supply with a low quality known for bugs or other flaw motherboard with a older refurb and no name brand SSD with the cheapest value RAM available.
One of my friends use to cut corners with new computer builds buy buying DOA systems off of ebay and yanking the CPU, RAM, and Hard Drive from the systems and scrapping the rest add a $50 motherboard and a $15 case to make it look like new and functional again, and then sell a computer with specs that would cost about $700 for $400 and he only had $150 into it for a nice $250 profit on about 2 hours of labor. The person buying the computer for $400 thought it was all new, but the CPU, Hard Drive, and RAM of a dead main board donor was used and so parts were not all new. Most people wouldnt know any better and assume that all parts are brand new, when in reality the DOA system that parts were used from took a lightning strike to the power supply and main board and so components that work from the DOA box could be stressed going into the new build that is sold with used parts.