Bad_Pool_Header is an aging/faulty hardware issue. I have come across it many times. The most obvious one is the RAM malfunctioning, which would have to be replaced. At times when working memories are replaced you might still face the same problem only to find out it is coming from the hard disk. What I usually do to solve the problem is as follows: 1. I replace the memory first because I have found out that often times I can clean install and face the same problem. 2. If that didn't work I replace the hard disk. 3. Dust and apply fresh thermal paste(when I am sure the cooling fan vents are clogged or the processor old thermal paste is completely dried up) 4. Do clean install of the operating system. These four steps have always worked for me flawlessly.
update: the power supply and one of my memory cards were dead. replaced the power supply and removed the defective RAM card and pc is working just fine. I'm surprised that my PC didn't slow down at all after removing 8 GB of RAM.
8gb is still ok by todays standard for average users who aren't heavy gamers, even 4gb is fine for a htpc or pc just for light games, you might run short of memory in some poorly coded AAA console ports but it'll probably use the page file, make sure that's on a ssd. i've seen battlefront 2017 use 2gb+ and other game 4-5gb but can't remember which one.