Can iMac 27 late 2009 enter TDM connected to a Mac Pro late 2013?

Thank you for replying.

But that doesn't explain why the iMac 27'' late 2009 isn't entering Target Display Mode.

I bought another Mini DisplayPort cable, and it's still not working.

I see lot's of people connecting the iMac 27'' to MacBook Pros without problems, but have never seen anyone connecting it to a Mac Pro 2013.

Please, if anyone managed to do this, please let me know.

I'm going nuts over this.

Thanks for your help.

I don't know what more I can add to the initial post.

The second Mini DisplayPort cable that I tried is Belkin, I don't think there are better cables for this, since Apple is not selling it anymore.

I did mentioned that if I restart the iMac, before logging in with any user, pressing command + F2 or simply connecting the cable will actually work, it shows up as a second display on the Mac Pro, I can move the mouse pointer on the iMac. But after about 2 seconds the iMac exits Target Display Mode, and after this pressing Command + F2 will only turn iMac's monitor black for about a second and not entering TDM anymore.

I even checked the firmware versions and both are up to date according to this.

It didn't work for me.

I did try all you cam imagine with the cables.

Maybe installing Snow Leopard could do the trick, but I give up already and bought a monitor.

I wasted so much time on this, I would hate Apple if the MacPro wasn't so awesome!

In the end it's better to use any monitor instead, even a cheap one. Takes less time to boot, uses less energy, is silent, etc...

Better luck to you! or start thinking about which monitor to use.

By the way, I was trying to use the iMac as a secondary display. If you are planning on using the iMac as your main display, save yourself some headaches and get a monitor.