Having a strange issue here that I can't figure out.
I have a Dell Inspiron 5675 desktop PC. It has a Radeon RX 580 graphics card in it. There is 1 HDMI port and 3 Displayports.
I just received the machine back from Dell support. They had to replace the graphics card because the fans weren't running on it. Everything appears to be normal again there. I noticed this problem before I sent it for repairs but assumed it was related to the faulty card at that time and I didn't thoroughly narrow down what the problem was. But it persists now.
I'm using this machine to be the brains of an arcade cabinet. As such, I have it paired with a 40" Samsung UN40MU6300 4K TV as a display.
The problem I'm having is that if I have the TV connected in any way whatsoever, the POST process will not start. I can power on the machine, it starts whirring, but no action whatsoever occurs until I disconnect the TV. If I pull the HDMI cable from the TV and plug it in to a different monitor, the POST process starts right away, the monitor senses the signal, and it turns on. Otherwise, it just sits there idle and none of the monitors connected will detect a signal. It seems to be willing to stay this way indefinitely. I have given it several minutes to get going but no luck.
I have tried every combination of connections I can think of. TV only, Monitor plus TV, 4 different HDMI cables, Displayport to HDMI cables, etc. As long as the TV is connected to the desktop in any way, the boot process will not start when powered on.
If I hook the TV up to the computer after it has started booting, it works fine.
I have searched the BIOS for related settings but can't find anything. No "halt on all errors" option or anything like that I can find. Nothing related to display at all that I can see.
I have an older Vizio TV that it works fine with, along with an Acer monitor that works fine. If either or both of those are connected (but no Samsung), the computer acts normally.
Anybody have any idea what's happening?