Mac Pro Mac Pro 5,1 Mojave, Sapphire RX580 no HDMI video

Discussion in 'Mac Pro' started by mikeka, Apr 24, 2019.

  1. mikeka macrumors newbie

    Jan 31, 2013
    Here's a head scratcher .... can't figure this one out. Mac Pro 5,1, Mojave 14.4, Sapphire RX580 video card.

    Video displays fine when using AOC monitors with DVI input. I use DVI to HDMI adapters to plug both monitors into the video card HDMI inputs. Looks great.

    However when trying to use a single new Dell monitor with only an HDMI input and connecting to the RX580 using just a standard HDMI cable no video is detected. Doesn't make sense.

    Any thoughts appreciated!
  2. hfg macrumors 68040


    Dec 1, 2006
    Cedar Rapids, IA. USA
    That is strange. Just yesterday I added a Sapphire RX580 to my MacPro 5,1 and did a fresh install / migrate to Mojave 10.14.4 and other than the expected no boot video, it is working fine driving a Dell AW3418DW Alienware monitor via the HDMI input.

    My 27" 5K iMac is also using that monitor via the DP interface.

    Hope you find your problem ...
  3. bookemdano macrumors 65816

    Jul 29, 2011
    Try a PRAM reset (Boot the cMP, and as soon as you hear the boot chime hold down Command+Option+P+R keys. Keep them held down through three boot cycles [so you will hear three more chimes--takes a couple of minutes], then let go. See if that gets your HDMI port to display.
  4. BlackScorpion macrumors member


    Sep 11, 2015
    Englishtown, NJ
    Has anyone ever resolve this issue? I'm still having the issue where after wake, only one monitor comes on, I have a MP5.1 with an Asus Radeon rx580. I have both monitors connected to HDMI ports. If the computer goes to sleep only one monitor comes back on, I have to disconnect the wire and reconnect it every time.
  5. bsbeamer macrumors 68020

    Sep 19, 2012
  6. Eschers macrumors newbie

    Oct 27, 2015
    Same here, I have a 28“ 4K Samsung U28E590D(hdmi 2.0) and a 24“ WUXGA Apple LED-Display(mDP to DP) on a RX580 Sapphire Pulse(as Apple recommends it, nevertheless it happens with a 580 Sapphire Nitro+ and a Red Devil RX590)

    What does temporarily fix my issue is this: when booting up my MP4,1(5,1) I can hear the fans of the gpu and/or cpu begin to change in rpm right before the screen gets a signal (due to no bootscreen as you all know) and then i quickly turn on the samsung screen manually instead of mac pro signal wake up, then it works just fine without any distortion whatsoever UNTIL the screen goes off(hibernate or screen saving) and from there its impossible to get a clear signal without restarting or pulling cables several drops every 4-5 seconds abruptly and then comes back and so on. Less often I experience a complete black screen

    Hopefully someone at Apple sees this and/or has already and a fix in new fw/sw
  7. SnakeCoils macrumors newbie

    Oct 17, 2018
    I had a similar problem with an old HP display (P222va) on its DisplayPort input: the HDMI signal from the various Radeon (HD7950 Mac Edition and flashed HD7950, HD7970, R9 280x) cards were not detected while the HDMI output from nVidia cards was correctly displayed. My first concern was about a mismatch between the flashed firmware and the video card model but since also the original HD7950 Mac Edition had the same issue the cause should be elsewhere.
    In the end I discovered the monitor was the issue and I simply changed the display, with a modern HP 22f display (HDMI and VGA input) that works flawlessy (except the same annoying bug in vertical centering on VGA input when the backdrop is almost black in the bottom part).
    Another issue with Radeon video cards is the analog VGA from DVI-I port: it is active during the boot process but becomes black (or out of range) when it reaches the Finder: at the time I solved this issue purchasing a miniDP to VGA adapter and it worked without any problems.
    Also, the flashed nVidia GTX 680 DVI-I to VGA worked on the same old HP monitor without problems.
  8. obiit macrumors newbie

    Jan 26, 2019
    I have had a few issues with HDMI on my Sapphire Pulse RX580 4gb and an Iiyama 27" where it wouldn't detect at boot. This happens randomly but sleep seems to be okay. I am trying it with Displayport to see if that resolves the issue. With Apple only saying it supports certain revisions of the RX580 there could be problems with the port configuration if your not using one of the "supported" ones?

    It could be the old HDMI handshake issue for HDCP if things aren't quite compatible? Try another cable if you have one or change your switch on order?
  9. BlackScorpion macrumors member


    Sep 11, 2015
    Englishtown, NJ
    Yeah, I tried using a different cable, gave the same issue. I will try a display port adapter to see if that helps. I rarely turn my computer off so, it's not the startup issue. Sometimes it so annoying, unable to get the second monitor going.
  10. obiit macrumors newbie

    Jan 26, 2019
    Just to feed back after about a week of shutting downs and sleeps i havn't had a failed start (i.e. no screen display) with a displayport cable. I did read somewhere (and only once) that mac's prefer displayport rather than HDMI perhaps it's actually true!? I am only using one monitor so that could be the reason it works?
  11. h9826790 macrumors G5


    Apr 3, 2014
    Hong Kong
    From memory, Apple never sell HDMI monitor. Thundetbolt, mDP, DVI, ADC, VGA...., but not HDMI.

    I won't be too surprise if HDMI has worst support in macOS.

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10 April 24, 2019