black screen pc problem

There are several steps that you can try though the symptoms are almost clearly indicating that there is a RAM failure. I am mentioning the steps below, please try them out in order.

Step 1: Check if your RAM is faulty. If it is possible for you to open your PC's cabinet and replace the RAM modules, then continue with that and check if your PC is working with another set of RAM module(s).

Step 2: If the problem persists even after installing a fresh set of RAM modules, assuming your are using Windows as your operating system, press F8 just after the BIOS messages show up to boot into 'Safe Mode'. Run your PC for a while to check if it is still hanging. If it does, then there are definitely something wrong with your drivers.

Step 3: Update all of the system drivers available for your PC. This includes Graphics, Networking, Sound, Chipset drivers.

Step 4: After updating the system with latest drivers and rebooting, if the problem still persists then run a 'Check Disk Scan' on your system disk, i.e. C: Drive. Right click on C: drive in My Computer and select 'Properties'. Under 'Tools' tab click on 'Error Checking' and click on 'Start'. The PC will restart and scan for errors on your hard disk. If there are some recoverable errors, Windows will automatically fix that for you. Otherwise, it is time to change your hard drive.

Step 5: If everything goes fine with Step 4 and your PC is still having the same problems, then it may be because of some malwares present on your computer. Time to download and install Malwarebytes from it's official website. After installing, please reboot your computer into 'Safe Mode with Networking' mode using the way I mentioned before. Scan the computer using the software, most likely malwares will be detected if present. Furthermore, you can also install 'Malicious Software Removal Tool' from Microsoft from their official link  and scan the PC in the same mode.

I hope your problems will surely be solved by performing all these steps.