Old iMac (mid 2010) used as external display with Windows laptops

[Twixt]

Hello,
I hope you guys are doing well.
Quick question about my old but still up and running (thx to this forum, SSD in place of optical drive and graphics card cooking), mid 2010 iMac (high sierra installed).
I have a 14inch thinkpad that I would like to connect to it, also planning to buy HP zbook at back to school for kid who would also need to use iMac as external display from time to time (both with Windows11).
There was no thunderbolt port on imacs at this time, and obviously no on current PCs.
I shall use mini display port that is available but will it work as both counterparties are not Macs? I asked AI but not convinced about the process and probability of success. Did you guys tried the same experiment ?
I ve found minidisplayport to HDMI and to USBC cables. which one shall I buy ?
Thank you in advance.

 

[Bigwaff]

Other way around. Whatever Thinkpad or HP zbook have for display out, you going to need (your display out)-to-mDP adapter.

 

[gilby101]

I have a 14inch thinkpad that I would like to connect to it, also planning to buy HP zbook at back to school for kid who would also need to use iMac as external display from time to time (both with Windows11).

To be clear:
Are you wanting to use the iMac as if it were a monitor? Can't do that without gutting the iMac and adding a display board.
Are you wanting to use some screen sharing software on the iMac which will connect via your home network to the Windows computers? There are numerous software solutions, but I am not clear if this is what you want.

 

[Twixt]

To be clear:
Are you wanting to use the iMac as if it were a monitor? Can't do that without gutting the iMac and adding a display board.
Are you wanting to use some screen sharing software on the iMac which will connect via your home network to the Windows computers? There are numerous software solutions, but I am not clear if this is what you want.

I only want to use iMac as a passive, 27" display screen. I love how leight and easy to use my P14 is but screen is too small for excel for instance

 

[Bigwaff]

I only want to use iMac as a passive, 27" display screen. I love how leight and easy to use my P14 is but screen is too small for excel for instance

iMac 2010 suppoerts Target Display Mode with caveats

Use your iMac as a display with target display mode - Apple Support

Target display mode is a feature available with certain older Mac models.

support.apple.com

Just get the correct adapter / cable.

 

[gilby101]

screen is too small for excel for instance

For that purpose you will get away with third-party screen software using your existing network connection. I would use Jump https://jumpdesktop.com/ which is a paid app on the client (your iMac) with free connection software to run at the server end (your Windows devices). There are lots of alternatives - I don't have the experience to recommend particular software in your situation.

Edit: I have removed my comments doubting Target Display Mode and gutting the iMac

 

[Nermal]

There is no need to gut the machine. Just put it in Target Display Mode and plug it in as if it were a DisplayPort display.

 

[gilby101]

Just put it in Target Display Mode and plug it in as if it were a DisplayPort display

Many apologies to you and @Bigwaff where I was doubting this working with Windows. Target Display Mode should work with the OP's iMac using its Mini-Display Port.

As some recompense for my doubting, here are two references.

How To Use an iMac as a Monitor for a PC

The iMac features one of the best displays on the market, and if you are lucky enough to have a 4K retina monitor, the vibrant screen is likely to make

www.alphr.com

How to Use iMac As a Monitor for PC [Step-by-Step Guide]

Have an older iMac? Using it as a monitor for PC is a good idea. Read this article to learn how to use iMac as Monitor for PC.

iboysoft.com

 

[Twixt]

Thank you guys for your help! will buy a cable and test that next week!

 

[Nguyen Duc Hieu]

I used my iMac 2010 27" as the monitor for my HP Prodesk 800 g1 SFF for a while back.
It was plug-and-play with a DP to miniDP cable.
The iMac must be powered on first to log-in screen.
The PC was powered on separately then plugging in the cable.
Video signal from the cable automatically switched the iMac to the monitor mode. Audio worked, too.
When the signal died (shutdown the PC), iMac switched back to High Sierra log-in screen.

 

[Twixt]

I used my iMac 2010 27" as the monitor for my HP Prodesk 800 g1 SFF for a while back.
It was plug-and-play with a DP to miniDP cable.
The iMac must be powered on first to log-in screen.
The PC was powered on separately then plugging in the cable.
Video signal from the cable automatically switched the iMac to the monitor mode. Audio worked, too.
When the signal died (shutdown the PC), iMac switched back to High Sierra log-in screen.

Thank you for your feedback. By DP to miniDP do you mean HDMI to miniDP?

 

[Nguyen Duc Hieu]

Thank you for your feedback. By DP to miniDP do you mean HDMI to miniDP?

No. I meant DisplayPort (normal size) to Mini DisplayPort (small size).

USB-C to mDP, or Thunderbolt to mDP might work as well, if your PC support the video output through those ports.

I had tried to search for HDMI to mDP before, but couldn't find the cable. Remember that the conversion adapter/cables are uni-directional.

The only thing solution available was HDMI to DP (active) adapter, then DP to mDP. It was more troublesome than finding a PC with DisplayPort. Most HP and Dell Workstations have this port, and almost all dedicate graphic cards has this DP port, too.

Others have confirmed that they could use iMac 2010 as monitor for Mac Air M1 laptop, so the Thunderbolt 3 (or 4) to miniDisplayPort cable/adapter does work.

 

[Twixt]

No. I meant DisplayPort (normal size) to Mini DisplayPort (small size).

USB-C to mDP, or Thunderbolt to mDP might work as well, if your PC support the video output through those ports.

I had tried to search for HDMI to mDP before, but couldn't find the cable. Remember that the conversion adapter/cables are uni-directional.

The only thing solution available was HDMI to DP (active) adapter, then DP to mDP. It was more troublesome than finding a PC with DisplayPort. Most HP and Dell Workstations have this port, and almost all dedicate graphic cards has this DP port, too.

Others have confirmed that they could use iMac 2010 as monitor for Mac Air M1 laptop, so the Thunderbolt 3 (or 4) to miniDisplayPort cable/adapter does work.

Thank you, I just received gear, will test that this week end. I assumed thinkpads have 2 ports for video out, hdmi and USB-C. As I wanted to keep USB-C ports free I went for HDMI to mDP via an amazon cable without adapter. Hope I did not miss anything about this uni-direction concept

 

[Nguyen Duc Hieu]

Thank you, I just received gear, will test that this week end. I assumed thinkpads have 2 ports for video out, hdmi and USB-C. As I wanted to keep USB-C ports free I went for HDMI to mDP via an amazon cable without adapter. Hope I did not miss anything about this uni-direction concept

If your cable is something like the one in the link below, I guess it will be OK. It will take 1 USB port of your laptop to supplement the voltage differential. Don't know if a common phone charger with USB-A port can be use instead.

StarTech.com 6ft (2m) HDMI to Mini DisplayPort Cable 4K 30Hz - Active HDMI to mDP Adapter Converter Cable with Audio - USB Powered - Mac & Windows - Male to Male Video Adapter Cable (HD2MDPMM2M)

Astonishing Picture Quality Clutter-Free Installation Convenient Connectivity

www.amazon.com

 

[Vladistone]

If your cable is something like the one in the link below, I guess it will be OK. It will take 1 USB port of your laptop to supplement the voltage differential. Don't know if a common phone charger with USB-A port can be use instead.

StarTech.com 6ft (2m) HDMI to Mini DisplayPort Cable 4K 30Hz - Active HDMI to mDP Adapter Converter Cable with Audio - USB Powered - Mac & Windows - Male to Male Video Adapter Cable (HD2MDPMM2M)

Astonishing Picture Quality Clutter-Free Installation Convenient Connectivity

www.amazon.com

Hello @Nguyen Duc Hieu !
in your signature I saw the same cofiguration of iMac 11.3 w/M6100 GPU and Monterey macOS as own...
My setup includes iMac 11.3 mid 2010 w/Monterey macOS with a patched by OCLP 2.4 the AMD Fire Pro M6100 GPU too, which worked in TDM mode until recently via miniDP for Mac mini M2 pro macOS 13.7.6
But as a result of updating Monterey to 12.7.6, I completely lost TDM.
So I want to know:
To what Monterey build do I need to roll back to work stably with TDM on iMac 11.3? Since I don't remember the number of the previous Monterey release...
Any other ideas on how to restore TDM?