Trying to connect my PS4 to my monitor.

[Borks]

**Before reading please note: I am not tech-savvy. If you have trouble understanding what I'm saying please feel free to let me know so that I may be able to explain!**

I'm having some trouble connecting my PS4 to my PC, not sure what is wrong or if I'm doing something wrong but I would greatly appreciate the help.
So here's whats up:
My monitor is an HP 23es and supports 1280x720 & 1920x1080.
It's connected to my tower via HDMI -(three ports in total) two of the ports on the tower are not working. Not sure why (I have never touched them until yesterday).
Every time I try to connect the PS4 to either ports and switch screen mode I get an error message saying something about "no input signal". It can't be my HDMI cable because I've tried 5 and they all work with my monitor. I've changed the PS4 resolution on my TV to 480p (Saw this on a video - said that should help), but that didn't work because I still got the "no input signal". I tried for a good hour to try and set it up but no luck.
Should I buy an HDMI - DVI cable? I would greatly appreciate the help.
Thanks in advance.

 

[popatim]

The HDMI ports on your pc are not inputs.
Since your monitor only has 1 hdmi port, you will need to purchase a hdmi switchbox. (something like This one)
Connect the pc and the ps4 to the switchbox, connect the switchbox to the monitor. Then you can use the switchbox to select which system will be displayed on the monitor.