Did 11 yrs as It in a HS, I have always had good results with HP or Acer monitors Square or Rectangle. That said I would agree the graphic card is suspect. Does the Ghosting start right away or over time?
Something that happens over time screams “heat” to me. Again, the graphics card can get toasty, especially in an older PC.
I know it sounds obvious, but has he opened the box and blown out all of the dust?
Could be a ghoin the machine. I have heard of such things.