|Some 2012 Mac Mini owners report Intermittent Loss of Video (HDMI)|
Saw several reports (and growing) in Apple's forums on 2012 Mac Mini Intermittent Loss of Video, with some cross posts in another thread. (Later several other threads were also started on the same subjects.)
One owner included a copy of his console log with several "display connect changed" and "No display devices are on-line" errors that coincide with these dropouts but not everyone noted/checked for those messages. (As always the first suspect is the cable/connection but some reports said same cable was used with other macs, same displays and were fine.)
(Updates) Some later replies noted getting their mini replaced and Apple reportedly is investigating this. I saw one report where a swap didn't help, one that said it did (so far at least). [Later several others said they exchanged their Minis but problem persisted.]
Intel Forum Thread on HD4000 Flickering:
Here's a thread started in mid-June 2012 titled Intel HD 4000 Graphics occasional flicker that suggests removing all but one ram module (running single channel) until you can update the motherboard bios with a fix. Here's a reply from Robert U. (Intel) on Sept. 25th (post #107):
"[Correct Answer] Re: Intel HD 4000 Graphics (i7-3770K) occasional flicker
This issue is a BIOS issue specifically with the Memory Reference Code (MRC) version 188.8.131.52 or older. Please contact your system or motherboard manufacturer for a system BIOS update for your system or motherboard that includes MRC 184.108.40.206 or newer.
If you have a system with 2 or more memory modules and are comfortable with removing all but one of them so that your memory is in single channel mode, try and remove all but one of them and the issue will go away. This can be used as a workaround until you are able to update your system BIOS from your system or motherboard manufacturer that includes MRC 220.127.116.11 or newer."
Even as a temporary workaround, running only 1 dimm isn't going to be acceptable for many. (And as of Early Nov, so far I've seen only 1 affected Mini owner say running 1 dimm helped. Not sure why I haven't seen the HDMI problem yet.)
I checked the EFI/Bootrom (and SMC) revs of the 2012 Mini I used (2.3GHz core i7 (mobile), 2x2GB ram - no flicker/dropout issues seen so far) and it is:
- Bootrom (EFI): 61.0106.B00
- SMC: 2.8f0
If someone w/repeated dropouts could post their info (in apple thread or via mail) I'd appreciate it to see if that's a factor. (Update: Replies from mini owners with dropout/flicker problems showed the same versions as above.)
There's also been more threads started on various display quality (washed out/gamma incorrect) problems, some (see example images 4th post down) appeared to be cases of wrong gamma/blown out contrast/white clipping. (I saw this also before creating a custom profile and monitor adjustments.) Similar complaints were reported by 2012 MacBook Air owners (also HD4000 graphics) using HDMI displays. Universal Access contrast setting wasn't the cause. I remember washed out displays/custom profiles (gamma) required even with my old G5 tower using a DVI 24in Dell LCD many years ago, but some of these recent examples seem worse. (BTW - There's also a past thread at Intel's forums on HD4000 black levels/RGB ranges.)
Some Samsung LCD owners with input naming options (i.e. some T27xxxx models IIRC) said renaming the Input to "PC" or "DVI PC" helped. (For monitors that have this option. My older 2493hm model doesn't.) I'd also check your display's brightness, contrast, color options - and I'd disable any 'dynamic' contrast/color mode.
HDTV Tip: Usually the best setting and sharpest text is a 1:1 mode on the HDTV - not the typical default 16:9 used for TV/tuner mode which has overscan. (Some HDTVs may call the 1:1 mode option "Just scan".) And try using Apple's 'LED Cinema Display' colorsync profile esp. if you have a modern IPS based HDTV. (If that profile does not appear in the listing, make sure "show profiles for this display only" is unchecked.)
While at the Samsung site to get a PDF for my old 2493hm, I noticed they had a firmware update notice (since April 2012) for SA Series LED Monitors that lists improved compatibilty and PQ.
(That note w/link was even at the top of my old CCFL 2493hm model page)
"SA Series LED Monitor Quality Improvement Announcement April 4, 2012.
Samsung has released a firmware update for Samsung SA series LED Monitors. This firmware update is for improved performance (better picture quality and PC compatibility).
If you have one of these models, Samsung recommends that you download and install the latest firmware update specifically designed for your monitor."
This may not be news to all SA display owners (and some may already have updated firmware) but posting anyway just in case. (The download is a PC exe.)
My Experience w/2012 Mini HDMI Video: (From Oct. 29th, updated early Nov.)
(Due to length after all the updates, added info, notes, etc I've moved this down a separate page on 2012 Mac Mini HDMI Video Problems/Notes and Tips.)