Getting 2nd monitor to work for iMac 27" 2013 model?

VikingOSX wrote:

I have an ASUS K272HUL 27 inch display connected to my 27 Inch Late-2013 iMac via DisplayPort cable

I have an ASUS K272HUL 27 inch display connected to my 27 Inch Late-2013 iMac via DisplayPort cable. Although the ASUS is plugged into power, it is powered off until I choose to use it.

Only when the ASUS display is powered on will I observe the Arrangement tab in the Displays panel. I use the following configuration so I can pass the mouse off the right-side of the iMac onto the adjoining ASUS display. This is useful for VirtualBox guests configured to use the secondary display.

I use an adapter from E-Bay that cost under $10.00. eBay item number: #383644263987

You get 2 for $12.99 The one thing you have to be careful of is not to stress the cable!

But it does work. I have used it with many flat screen, computer monitors, & any HDMI input.

Yes, you just need a good Mini DisplayPort to DisplayPort cable.

https://www.amazon.com/s?k=mini+displayport-to-displayport+cable

It should not matter which macOS you are running.

I would first check in the monitors menu, to see if you have the source input set correctly.

If that doesn't work or help, maybe there is something wrong with the monitor.

To check the monitor, I would test the monitor on a different computer.

It’s fairly uncommon for those port to completely die, because I’m pretty sure that they are protected by internal overloads like the USB ports. I would try resetting the SMC again, only this time leave it disconnected from the power for 5 or 10 minutes.

Sorry but I have no idea if using USB in bootcamp will work or not. Mostly because I have never, nor ever plan on installing windows on any of my Mac’s.

vincentnyc wrote:

SMC reset didn't work after 10 minutes of disconnecting the power. Since I don't want to take it to apple repair.

It was worth trying, NO?

I'm only left with 2 options: try another monitor and downgrade my mac os to the original maverick. you mention downgrading mac os won't work. why do you believe that after i show you a thread about ppl upgrading to catalina and all of a sudden their 2n monitor doesn't work anymore? how do you explain that? i have 2 ssd on my imac. one is a 120 GB and the other one is a 1 TB. Both are running catalina. i'm currently using the 1 TB as my main to boot up. maybe i can downgrade using the one that has 120 GB back to maverick and see if that would work? if that doesn't work, i can go back using my 1 TB sdd? what do you think?

You can try an HDMI TV with a Mini DisplayPort to HDMI adapter, but that connection is generally more finicky than the DisplayPort or DVI monitor connections.

Because I've been running dual monitors on my Mac's for many many years and none of the macOS versions, have ever disabled or stopped an external monitor from working.

is there a diagnostic somewhere i can run to test if my thunderbolt ports are working properly or not?

How to use Apple Diagnostics on your Mac - Apple Support

vincentnyc wrote:

i'm running the diagnostic later tonight by holding down the d button while rebooting. do you think this will help anything or a waste of time?

Yes it could very well return a hardware problem.

i'm returning the staples cable and ordering one more cable just to see if it is really the cable or not. the one i'm ordering is from amazon and it does said thunderbolt compatible:

https://www.amazon.com/gp/product/B00C7RJQPY/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

Yes Cables Matters makes good cables.

The 27" 2013 iMac has 2 Thunderbolt ports.

https://support.apple.com/kb/sp688?locale=en_US

If neither of the 2 ports are working to drive a monitor, then I really dough that a TB Hub will help.

I think' that you need to take the iMac to an Authorized Apple Service Provider and have it checked.