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Random Black Screens

michael_aos said:
They said they would look at it...
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Does that mean you didn't actually go there in person yet? Frankly, I'd be looking to get a replacement unit ASAP. It seems like you have a hardware problem.

One item that recently occurred to me is that I've got 16GB of RAM from OWC. I've not tried dropping to a single DIMM, nor have I tried going back to the original 4GB of Apple RAM.

It also SEEMED like the EFI Update complained during the install, but it flashed by too quickly for me to be sure. The Boot ROM version is consistent with a valid EFI update, and when I try to manually install it, it says it's already installed.
Click to expand...

Ah-ha. Now maybe you're getting somewhere. It's entirely possible to have a bad ram chip. I forget what it's called, but I had a program I used when I upgraded my PowerMac to 1.5GB and its CPU to 1.8GHz to test the memory over an extended period of time from a cold boot. I was having problems with sound disappearing in OS9 (appears to be related to the CPU upgrade) and I had to make sure it wasn't memory related. Not that it mattered, the company wouldn't do anything about it (Newer Technology G4 upgrade) so I pretty much gave up any hope of playing old OS9 games at that point (productivity that didn't need sound was fine, etc., though, but I would get sound about 1/3 times on the first boot to OS9 after a reflash, but I wasn't going to do that every time I wanted sound in OS9 and it would stop working again on the next boot).

Anyway, my point is it would be a good idea to try swapping back to the original memory and see if it makes any difference or at least test the new memory extensively to be sure there's no issue with it (frankly, it'd be easier to just swap back; the new Mini is very easy to open).
 
MagnusVonMagnum said:
Does that mean you didn't actually go there in person yet?
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I was there at 9:50am for my 10:00am "appointment". Turns out they don't open until 10:00am.

Not sure what the value was of having an appointment. They checked me in and then I waiting ~10 minutes for someone to get to me.

Apparently nothing I had told Apple previously was included in my case. I explained everything to the pleasant-but-clueless person at the Genius Bar. He took my information, then bagged-and-tagged the Mini for an overnight stay with someone in the back room.
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Just got another monitor using HDMI -> HDMI and every few hours I get a screen flicker :( the text seems kinda blurry aswell and the colour seems a bit on the yellowish side...
 
MagnusVonMagnum said:
It's entirely possible to have a bad ram chip.
Click to expand...

Yep, I think so too.

I had read about a potential issue with the Intel HD4000 chipset and having 2 DIMM's installed. Might have been something with interleaving. The author suggested removing one DIMM for testing. I kind of blew it off, as I simply wasn't interested in using the Mini with <16GB of RAM.

I believe the 16GB of RAM is shared between the OS and (768MB) video chipset.

I'm kind of kicking myself for not thinking about the RAM sooner.

When I get the Mac Mini back from the Apple Store, and it still has the issue, that's the first thing I'll check.
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Dropped it off at 10:00am Friday 1/18, so they could run extended diagnostics.

Nothing heard Friday.
Nothing heard Saturday

Finally called them Sunday evening. The "genius" was able to find my case in the computer, but struggled to decipher the current status.

He thought maybe they were able to duplicate the issue, but he didn't sound very confident.

He assured me it was "next in line" for repair, and that they would be doing repairs today (1/21 - MLK holiday).

I would not be at all surprised if I don't hear from them today either.
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Still no update.

I called again on Monday evening.

They still insisted my box was "next". Now they said the repair guys only work at night, and it typically takes 3-5 days.

So -- 3 different people, 3 different stories.

I asked them to make a note for someone to call me today with an update.

I don't think the people who answer the phone at the Apple Store have any clue at all how repairs are processed.
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No joy at the Apple Store. They said they couldn't duplicate the problem (not at all sure that they tried). I took it home and was able to get a black-screen within 2 minutes.

I booted from another HD and installed the 10.8.2 supplemental update 2 on the Fusion drive. No change.

I haven't found any pattern to the random black screens, but I have found that I can consistently get the screen to black if I play a Flash video in full-screen for a minute or so.

I've gotten the random black screens even on a new OS install without Flash installed though, so it's not Flash per se that's causing the problem.

I went ahead and removed Flash from my primary boot drive (Fusion) anyway.

I've also contacted a 3rd Party Authorized Apple repair facility and I can have them look at it if the issue continues.
 
Just a quick update.

I haven't had a single black-screen yet since uninstalling Flash.

I want to reiterate that I HAVE gotten the random black screens in the past when running a new install of the OS on a different disk that doesn't have Flash.

I've also gone a day or more in the past without a black screen, even with Flash installed.

It seems like it could be a contributing factor though.
 
Another update -- several times today my Apple display (in this case, it's the Thunderbolt display) went "black", but as soon as I moved the mouse it flicked back to life. It's almost like it went to sleep. I don't have any hot-corners defined and Display Sleep is set to 1hr (when on Power).

I'm also using both screens interactively when this happens.

I finally got a unrecoverable black screen this afternoon.

It so happens I was running HP Virtual Rooms, but I don't know if that really "caused" the issue. Still no Flash installed.
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michael_aos said:
I'm kind of kicking myself for not thinking about the RAM sooner.

When I get the Mac Mini back from the Apple Store, and it still has the issue, that's the first thing I'll check.
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Click to expand...

Did you check this yet? It sounded like you would, but there's no update about it.
 
I had the momentary black screen issue pop up again on my 2012 mini, again using the Thunderbolt out with a DVI adaptor to a 20" ACD.

This time, the momentary black screens continued about once every couple minutes while I was on a social networking site where I was continually scrolling down and more content kept loading at the bottom as I was scrolling. Perhaps this was enough of a graphics and/or CPU load to cause the issue to repeatedly occur, because as soon as I quit Safari, the black screens stopped.

Up until then, it had only occurred a few random times over the past 4 months or so.

Again, the problem I am seeing is simply the screen goes black for about a second then comes back on again, and it's not a screensaver or hot corner issue - mouse pointer is in the center of the screen.
 
ctone said:
I had the momentary black screen issue pop up again on my 2012 mini, again using the Thunderbolt out with a DVI adaptor to a 20" ACD.

This time, the momentary black screens continued about once every couple minutes while I was on a social networking site where I was continually scrolling down and more content kept loading at the bottom as I was scrolling. Perhaps this was enough of a graphics and/or CPU load to cause the issue to repeatedly occur, because as soon as I quit Safari, the black screens stopped.

Up until then, it had only occurred a few random times over the past 4 months or so.

Again, the problem I am seeing is simply the screen goes black for about a second then comes back on again, and it's not a screensaver or hot corner issue - mouse pointer is in the center of the screen.
Click to expand...

If it does it consistently and repeatably you have something wrong....I'd take it in to Apple.
 
There seems to be a connection to the RAM.

I pulled the 16GB from OWC and installed the original 2x 2GB factory RAM.

HD 4000 video RAM dropped from 768MB to 512MB.

Installed Adobe Flash and played several videos in full-screen.

No hiccups, no issues at all.
 
I installed one of the OWC 8GB sticks, bringing the installed total to 10GB.

Video RAM says it went from 512MB to 768MB.

Doesn't appear to be any issues in this config either.

I'm planning to swap-in the other 8GB stick and sure hoping the problem shows up immediately.
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I paired each of the 8GB OWC sticks with a factory 2GB, for a total of 10GB.

Tested each by playing a Flash video in full-screen on the Apple display. No issues at all.

Paired the 2x 8GB OWC memory for a total of 16GB and got the black screen again as soon as I started the flash video in full-screen.

I don't know if the issue is related to having 10GB -vs- 16GB, or if maybe these two 8GB sticks just don't play nice with each other or what.
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michael_aos said:
I installed one of the OWC 8GB sticks, bringing the installed total to 10GB.

Video RAM says it went from 512MB to 768MB.

Doesn't appear to be any issues in this config either.

I'm planning to swap-in the other 8GB stick and sure hoping the problem shows up immediately.
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Click to expand...

If the GPU video shared memory is mapping to the slot that the 2MB stick is in (for example the first slot...which would be my guess is the critical one for the GPU shared memory) then all that tells you is that the stock memory works with the GPU as shared memory. If that is the case then both OWC 8GB sticks could be swapped out of the same second slot for a total of 10GB and it might still work...even if one or both of those 8GB sticks aren't working right together.

Try installing the two OWC 8GB sticks in the two slots and see if the video problem shows up again. If it does then swap the two sticks and see if the video problem also shows up in that configuration. If one of those configurations doesn't work and one does work then that means one of those 8GB sticks is likely bad or incompatible for video memory and will need to be replaced and the other 8GB stick would be good. If the video problem shows up no matter which slot the 8GB sticks are in then both sticks are probably incompatible (possibly a timing issue) for shared GPU memory.

Either way OWC will be able to replace the RAM kit if it isn't working for your machine. If you still have an issue with replacement memory then there may be a general video issue related to the timing of that particular DDR3 RAM that for some reason wasn't identified before (by OWC) and the only solution for that would be to use different RAM sticks that are compatible.
 
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SoCalReviews said:
If the GPU video shared memory is mapping to the slot that the 2MB stick is in (for example the first slot...which would be my guess is the critical one for the GPU shared memory) then all that tells you is that the stock memory works with the GPU as shared memory. If that is the case then both OWC 8GB sticks could be swapped out of the same second slot for a total of 10GB and it might still work.

Try installing the two OWC 8GB sticks in the two slots and see if the video problem shows up again. If it does then swap the two sticks and see if the video problem also shows up in that configuration. If one of those configurations doesn't work and one does work then that means one of those 8GB sticks is likely bad or incompatible for video memory and will need to be replaced. If the video problem shows up no matter which slot the 8GB sticks are in then both sticks are probably incompatible for shared GPU memory.
Click to expand...

Thanks. Good catch, and good thinking.

I did have the 2GB stick in the 1st slot.

Starting over...
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Installed just 1x 8GB OWC DIMM. Video RAM reported as 768MB.

No issues. Repeated with the other DIMM. No issues.

Installed both 8GB OWC DIMM's (16GB total) and immediately get the black / blank screen when playing a Flash video in full-screen.

I'm thinking the problem is either related to having 16GB of RAM, or maybe when I have 2x identical DIMM's there is some interleaving / striping of memory that these particular 2 DIMM's can't handle?
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michael_aos said:
Thanks. Good catch, and good thinking.

I did have the 2GB stick in the 1st slot.

Starting over...
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Click to expand...

I have a more than a decade and a half of experience diagnosing hardware problems on PCs so I am used to solving these kinds of problems. I am relatively new to Macs and OS X so you will see me asking a lot of questions in this forum about software and OS X but debugging the hardware issues is similar for all Intel based machines. Note also that I edited my original post with a few additional suggestions of how to determine which of the 8GB sticks or if both are causing this video problem. I look forward to what you find out after more testing.
 
Well I'm back to 10GB of RAM. 8GB OWC in bank0 & 2GB Apple (Samsung) in Bank 1.

Curiously, it says "10 GB 1067 Mhz DDR3".

When I go into the System Report, it also says Speed: 1067Mhz.

I could have sworn it said 1600Mhz in every other combination.
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When I have just the single 8GB OWC DIMM, it's reported at 1600Mhz.

As soon as I add either of the 2GB Apple (Samsung) DIMM's to get to 10GB, it reports they're both running at 1067Mhz.

Is this by design? Mis-matched sizes run at 1067Mhz and identical sizes run at 1600Mhz?

That could go a long way toward explaining my issue here -- one or both of these 8GB DIMM's might be find at 1067Mhz but not happy when driven at 1600Mhz...
 
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