Trying to use my iMac in Target Display Mode

[InfoTime]

Just built a PC with a Sapphire Radeon HD 5770 card. Using the Displayport cable to connect to a 2009 model 27" iMac.

As soon as I switch to Target Display Mode on the iMac the PC screen starts flashing. The Mac's screen goes black indicating that it's "switched".

What I've tried so far:
- originally had Windows automatically download the driver for the board
- installed the driver from the CD that came with the card.
- start the machine with just the iMac hooked up
- use most possible combinations of the cards two DVI ports for the 1st display and the HDMI port (card has 2 DVI, one HDMI and one Displayport).
- did a a totally clean install of the Windows 7 64-bit, wiped the hard drive completely. Did not install any additional drivers to the machine other than the ones that Windows 7 itself installed - so the machine is completely "stock", then downloaded the latest driver from Sapphire's website. I put that driver on a flash drive and installed it and rebooted.

A few times the Mac's screen has turned blue momentarily. Sometimes the display properties on Windows will show the second display as being detected.

I called the company that sold me the cable. The rep immediately diagnosed it as a bad cable and sent me a new one. The new one behaved exactly the same.

I have a ton of computer equipment and accessories lying around. Unfortunately very few Displayport devices.

I do have a MacBook Air (fall 2010 version) and a MacBook Pro (fall 2008 model). I don't have a mini Displayport to mini Displayport cable to test with, but I may go buy one at the Apple store.

I have a regular Displayport to Displayport cable that came with a client's Dell monitor. I may ask him to borrow the monitor.

At this point I don't know if the problem is with the iMac, the cable, the PC graphics card or the PC

I bought the cable from Circuit Assembly based upon a comment in a review of another cable on Amazon that a lot of reviewers were saying didn't work right at all. CA seems to have a pretty good grasp of this cables usage. I bought the 5 meter version, which I suspect may be the culprit (but the guy at CA dismissed that as a possibility). Here's the cable I bought:

http://estore.circuitassembly.com/products/Mini-Displayport-to-Displayport-Adapter-Cable.html

Anyone have any thoughts?

 

[oliwa]

same issue

I'm having the exact same problem with mine, its a display port iMac 27 but i can't get the target display mode to work at all, i've tried with my thunderbolt MBA and my display port MBA neither work, and the main issue is that my belkin AV360 quit working all of a sudden and i can't use it as a display for my xbox either. i'm very frustrated but it seems like an issue with lion to me. i managed to get a brief flash of the xbox splash screen for half a second or so but thats all, everything else is static or red horizontal/vertical lines. just bought mass effect two today as well! urgh!

 

[InfoTime]

Why do you think it's Lion? The OS hadn't entered my thought process as a potential explanation.

I could test it easily enough. I have an external drive with my Snow Leopard install for the iMac. I could boot from it and try it.

 

[InfoTime]

The OS is not a factor in my situation.

I rebooted my iMac from an external drive with Snow Leopard 10.6.8. Behaved exactly like it does with 10.7.2.

 

[InfoTime]

Borrowed a Dell 2408WFP display and used a Displayport to Displayport cable. Worked perfectly.

Got two cables arriving tomorrow:
- a Mini Displayport to Mini Displayport to see if a Mac laptop can drive the display
- another Displayport to Mini Displayport cable, which is what I started out with but from a different manufacturer.

So for now I know that my PC can drive a Displayport display. I'll soon know if my iMac is compatible.

 

[InfoTime]

PC graphics card that will successfully drive a 27" iMac in Target Display Mode?

I'm building a PC and want to use my Late 2009 27" iMac in Target Display Mode for the PC.

Here's a summary of my build:
Motherboard: Gigabyte Z68XP-UD5
Processor: Intel Core i7 2600k
Video: SAPPHIRE Vapor-X 100283VX-2L Radeon HD 5770

No matter what I try I can't get the iMac to function as the display for this setup. Here's a summary of what does work:

• MacBook Air (Oct 2010) to iMac with Belkin Mini Displayport to Mini Displayport cable
• PC to Dell 2408WFP with Dell-supplied Displayport to Displayport cable

So I believe that most of my hardware is good. The only thing that doesn't work is the PC to iMac - which is the main thing I wanted!

I started out by purchasing what seemed to be a highly recommended vendor and their cable for this purpose.

http://estore.circuitassembly.com/products/Mini-Displayport-to-Displayport-Adapter-Cable.html

I've now tried two of their cables as they thought maybe the first one was defective. I also ordered a Displayport to Mini Displayport cable from Startech (via Amazon). All three cables behave the same.

As soon as I switch to Target Display Mode on the iMac the PC screen starts flashing. The Mac's screen goes black indicating that it's "switched". A few times the Mac's screen has turned blue momentarily. Sometimes the display properties on Windows will show the second display as being detected.

There are some instances where the PC screen doesn't flash. Like right after a clean install using the standard VGA driver that Windows 7 installed. But it still wouldn't drive the iMac's screen.

I've installed Windows clean, twice. This is a brand new machine that has nothing on it. After the first build and attempt at this I did another clean install and then installed the latest drivers from the manufacturer's website.

Seems that there may be a compatibility problem with this card. Someone posted about this on another forum:

I've found out, too late, that the 5770 has enormous problems in this area - seems to be a hardware or BIOS issue that isn't going away any time soon.

So, I'd like to find a way to make this card work or find a card that is known to be compatible with this arrangement. It doesn't have to be a really high-end card. I play Unreal Tournament 2004 which is old and shouldn't be too demanding by today's standards. Of course I wouldn't mind getting a card with a little bit of power to try some newer games.

Can anyone guide me to a solution to this, either fixing the card I've got or selecting a known compatible card?

 

[InfoTime]

OK, looks like there's been a known issue with the 5700 and 5800 series cards for over TWO ****** YEARS. Here's a few highlights from a 20 page thread where this has been discussed.

http://hardforum.com/showpost.php?p=1034892655&postcount=43
http://hardforum.com/showpost.php?p=1034907202&postcount=58
http://hardforum.com/showpost.php?p=1034914499&postcount=62
http://hardforum.com/showpost.php?p=1034980226&postcount=128

Sapphire reports it's a known issue:
http://hardforum.com/showpost.php?p=1034983120&postcount=132

Inexpensive low-end card that works:
http://hardforum.com/showpost.php?p=1035685197&postcount=231


10/2010 list of known working cards:
http://hardforum.com/showpost.php?p=1036326695&postcount=336

1) Radeon Eyefinity cards all seem to work .... advanced switching technology
2) Radeon 5900s with mini displayport
3) Radeon 4000 series with displayport ( use a mini displayport to displayport cable)
4) Radeon 3000 series with displayport ( use a mini displayport to displayport cable)

SAPPHIRE HD 6870 1GB GDDR5 PCIE with Eyefinity looks like a goer for the money.
99% sure this will work.
http://www.sapphiretech.com/presentation/product/?psn=0001&pid=496

Most of these cards are $300 or more. I just ordered this Radeon 6870 card that has Eyefinity from Amazon. Hope this works!

 

[staralfur]

Did you get it working in the end pal?

 

[InfoTime]

Thanks for asking. The answer is yes.

The card I ordered from Amazon was definitely compatible. I installed the card, hooked the Mini Displayport to Mini Displayport cable from the card to my iMac (no other video connections made), turned on the PC. My iMac immediately switched to Target Display Mode and displayed the POST messages and BIOS splash screen the proceeded to boot into Windows.

It behaved the way you'd expect a standard interface like VGA or DVI to behave. That's what I had assumed Displayport would do too. Didn't know there were such rough edges.

So the card worked great! Then I sent it back.

Reason: the bastard 3rd party seller on Amazon sent me a used card. And not just a card that had been previously opened and put back in the box:
- the seal on the box had been broken and taped over
- the sticker on the card that all the reviewers said falls off over time was gone.
- the fan made noise that was not consistent, like a bearing was potentially failing
- there was an accumulation of dust on the top of the board, I'd estimate about three to six months of usage.

 

[staralfur]

Pity about the amazon chancer but good that you know the card works. I'm going for the HD 6950 so hopefully all will run as smoothly for me.

Did you received a mini dp to mini dp cable with the card or did you buy one? If so, which one?

Thanks for your help.

 

[InfoTime]

I used this cable that I bought from Amazon.

Oh, and I have more good news. Newegg didn't accept my return of the Sapphire 5770 card and is sending it back to me. They won't accept it because I had cut the UPC code off the box for a rebate.

I'm going to try to get Sapphire to upgrade me to a card that works.

 

[akm3]

These things are never easy are they

So I'm trying to do the same thing as you (Build a PC that uses the iMac as a monitor, while being able to easily switch back and forth to the iMac.)

Your advice of the crucial piece of info is you have to have a compatible card which you listed as all Radeon 6870's fitting that bill right? So if I just buy a MDP 6870 I'm golden right?

 

[InfoTime]

I'm pretty sure you'd be in good shape. Make sure of course that it has a Displayport connector. In summary I believe most cards work except for the 5700 and 5800 series. Check the posts at the hardforum.com links I posted above.

 

[InfoTime]

Newegg wouldn't take my card back since I'd already submitted the UPC with the rebate. Shipped them the card on November 8th, got it back December 6th. Wow - that's fast!

Anyway, I've submitted a ticket with Sapphire:

This card is not compatible. I bought it because it has a standard Displayport output. This output will not drive my iMac in Target Display Mode. That is the sole reason I selected this card.

After spending many frustrating hours figuring out the cause of the issue I learned that there is nothing I can do to fix it. Nor is there anything you can do. Apparently there is a timing flaw in the ATI chip. A flaw that has been corrected in newer / other products from ATI. The flaw has been confirmed by many users on the Internet. The flaw was confirmed by Sapphire to one user two years ago.

See https://forums.macrumors.com/threads/1264950/ for the details of what I went through and the references I found that prove this is a problem.

I tried to send the card back to newegg but they wouldn't take it back since the UPC code was used for a rebate. I was told to take up the matter with the manufacturer of the card.

Since it is my firm belief that simply replacing this card with another card in the 5770 series I expect a refund of my purchase price (approx $120 US) or a trade-in of the card toward a model that is compatible - such as the SAPPHIRE Vapor-X 100315VXL Radeon HD 6850 1GB 256-bit GDDR5 PCI Express 2.1 x16 HDCP Ready CrossFireX Support Video Card.

Please let me know whether you plan to give me a refund or let me know how much the price would be to upgrade to the SAPPHIRE Vapor-X 100315VXL Radeon HD 6850 1GB 256-bit GDDR5 PCI Express 2.1 x16 HDCP Ready CrossFireX Support Video Card.

Let's see if they make it right or tell me to pound sand.