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I have the very new Asus PB287Q 4K monitor and I've enabled display port 1.2 in its OSD menu system, but my Ubuntu 14.04 laptop still isn't using 3840x2160 at 60hz - it's stuck at 30hz. I'm curious what's the correct way to get this to 60hz?

I have an ATI Mobility FireGL M8900 and I'm using fglrx.

01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Blackcomb [Radeon HD 6970M/6990M]

fglrx:
  Installed: 2:13.350.1-0ubuntu2
  Candidate: 2:13.350.1-0ubuntu2
  Version table:
 *** 2:13.350.1-0ubuntu2 0
        500 http://us.archive.ubuntu.com/ubuntu/ trusty/restricted amd64 Packages
        100 /var/lib/dpkg/status

Here is the relevant xrandr output:

DFP5 connected 3840x2160+1920+0 (normal left inverted right x axis y axis) 621mm x 341mm
3840x2160      30.0*+
2048x1536      30.0
tamale
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  • do you have a crossfire? – Nick Bailuc Jun 26 '14 at 22:57
  • No, this is an M6600 Dell Precision laptop with the M5950 FireGL card. – tamale Jun 27 '14 at 04:22
  • What are you not gwtting 60herts in. Desktop? Or an application like a game? – Nick Bailuc Jun 27 '14 at 04:24
  • Like, at the X level.. I can see the modeline in use with xrandr and it's 30hz – tamale Jun 27 '14 at 13:39
  • I said 5950 above and I realize that was wrong.. I meant M8900. – tamale Jun 27 '14 at 17:49
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    http://askubuntu.com/questions/147580/how-to-see-change-screen-refresh-rate-or-monitor-frequency – mmm3743 Jul 07 '14 at 15:56
  • Are you sure you aren't connected via HDMI rather than display port? Specs from http://www.asus.com/Monitors_Projectors/PB287Q/specifications/ True Resolution : 3840x2160 at 60Hz (DisplayPort) ,3840x2160 at 30Hz (HDMI) – Elder Geek Jul 07 '14 at 17:05
  • I am sure I'm connected via display port. I don't have a cable in my laptop's HDMI port at all. I'm using a direct display port to display port cable from my laptop to the monitor. – tamale Jul 07 '14 at 19:15
  • Regarding the suggestion to check http://askubuntu.com/questions/147580/how-to-see-change-screen-refresh-rate-or-monitor-frequency ...

    I pasted the top output of xrandr in my question - the 60hz modeline isn't being reported by the monitor (even though there are numerous reports of people successfully getting this monitor to work at 60hz on windows)

     – tamale Jul 07 '14 at 19:16
  • Perhaps you can verify that your monitor works at 60 Hz on another system. This would make it clear whether the problem was with the monitor or the system. – Elder Geek Jul 13 '14 at 18:04
  • My monitor works at 60hz on the same laptop in windows 8. – tamale Jul 14 '14 at 14:50

1 Answers1

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Research indicates that for the Dell Precision M6600 laptop you may need the latest linux beta driver

Available here: http://support.amd.com/en-us/kb-articles/Pages/latest-linux-beta-driver.aspx (version 14.6 at this moment. Supports 12.04.4 and 14.04)

I realize this isn't a canonical answer but it may be helpful in your situation.

I believe that this answer already covers the vast majority of this type of question: How to see/change screen refresh rate or monitor frequency?

If this doesn't work I would contact Dell to discuss your warranty status.

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Elder Geek
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  • I have the Dell M6600 with the ATI Mobility FireGL graphics card, not the nVidia/optimus/quadro one.

    It's also worth noting that I'm using display port just fine with the monitor now, it's just running at 30hz instead of 60hz.

     – tamale Jul 07 '14 at 19:14
  • What's the BIOS version? – Elder Geek Jul 07 '14 at 20:46
  • I have the A12 bios currently, but I could try upgrading. Checking the release notes of the A13, A14, and A15 updates there is nothing that mentions my graphics card or anything else which I would think would apply here, though. – tamale Jul 08 '14 at 14:36
  • Added link to Dell warranty status page. – Elder Geek Jul 09 '14 at 11:36