Ilustrated mystery: HD4890 does not detect second PC monitor, only TV

My brain is about to explode. Please help!
My HD4890 card has two ports. It's been working with dual monitors for almost two years. No trouble. Two weeks ago I had to use Extend Desktop and Detect Display in order to activate the secondary screen (HP). A few days ago the screen completely stopped working. Unless I connect it to the main port. See below for an illustration of my issue.
My system is a Intel Core i7 920 Quad-Core Socket, 2.66Ghz in a main board ( Asus P6T Deluxe V2) with 6GB RAM (Corsair).

Is there anyone out there smart enough to see where I'm failing?

Scenario 1: Sony monitor works. (Port 1) HP monitor does not. (Port 2)
My first theory: Port 2 or the connector is broken.

Scenario 2: Sony monitor works. (Port 1) Sony TV works. (Port 2) (Different, longer cable) My second theory: HP monitor or the short cable must be broken.

Scenario 3: HP monitor works! (Port 1) Sony monitor does not. (Port 2)
My third theory: WTF?
13 answers Last reply
More about ilustrated mystery hd4890 detect monitor
  1. That is the same problem I have had with my 6950's and 470's. It seems that you cannot use multiple monitors while using HDMI.
  2. On second look, it appears you did get it to work with one setup. In that case, did you have speakers on the monitor that the HDMI long cable worked? I wondering if the use of HDMI with sound would effect the result.
  3. I had the monitors connected and running perfectly for two years. I used external speakers, but six months ago I switched to alternating between the speakers on the HP monitor and a mini jack headset.
  4. I wonder if the use of monitor speakers has an effect. When I attempted to use HDMI on my monitor and use another with DVI connection, I had sound feeding monitor speakers and it also would not let me use a 2nd monitor, but it does with DVI on both.
  5. I'm actually wondering about driver issues, since the 4890 is a sort of special card.

    What are the settings in Catalyst?

    I assume something might have happened within the last few days for it to stop operating.

    There is a 'long test' that requires a linux livecd to test OS dependance.
  6. Bystander: Unfortunately the HP monitor only has VGA and HDMI ports. The card has two DVI ports. Since I don't have a VGA-DVI converter, I have to use my HDMI cable.

    Firefyte: I've reinstalled the Catalyst Control Centre several times, and also tried different versions. I've tried the force detect settings as well, with no luck. I also selected 'Restore Factory Defaults', but with no effect.

    A linux livecd? Where would I get such a thing?
  7. You can get a live CD of linux here:

    download, burn to DVD, or copy to a USB stick, boot from it, do a bit of mucking about to see if you can get two monitors to work (google should be your friend for this). Most of the time, just having them connected should make it work out of the box.

    What exact make of the 4890 do you have, bios updates, change of port on MB? We're running out of options fast, unless there's something a bit more fundamental wrong.
  8. Here's one more bit of info: My games and Photoshop tell me that the video hardware I have is unrecognized, yet they still run as normal. :-S Is there a way I could be installing the CCC wrong?

    I've never used Linux. Is that what I would be installing through the ubuntu download?
  9. There used to be a catalyst uninstaller but it's probably ancient by now.

    Tthere may be a point to the unrecognized hardware, you can check in device manager if there are a few ghosts lying about, a full uninstall of CCC and related drivers might be in order.

    Yes, this would be essentially for a live version of linux (ubuntu variant), but lets keep that option until the new 'issue' is dealt with.
  10. Hi Firefyte! Thanks for your help!
    I've been in the device manager; there's no ghosts there as far as I can see. I also tried uninstalling the CCC and reinstalling it a while back. No effect.
    I feel like I'm ignoring something important; like drivers for the HP monitor or something, but I've tried installing those and it doesn't work. The HP monitor runs on drivers provided through Vista I believe. As seen here:

    NOTE: For the supported Microsoft Windows Operating Systems, Microsoft Windows
    Hardware Quality Labs (WHQL) certified monitor drivers are installed.
  11. Half of the time, monitor drivers shouldn't make any difference. I never installed mine.

    I think we do need slight recap of what we have tried, and failed at. But we are running out of options. The Linux route sounds a bit difficult, but might be worth a shot, just boot it up, if it shows as dual monitor (you can go into administration -> preferences (or something) to change the settings to see if it doesn't work). Normally, this works out of the box, so give it a shot. If not, we can almost certainly point towards a hardware failure, or other options (changing PCI-E slot, if possible).
  12. Hey Firefyte! I was about to get the Linux when... suddenly the HP monitor worked again. I wonder if it has something to do with me uninstalling Soundmax, a program I used to keep track of the different audio inputs on my PC. I will check to see if things work now. If not: Linux it is!
  13. Well, it might be wanting to use the HDMI port in mysterious ways, but as long as it keeps working...
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