Mac Pro 3.1 black screen, loud fans

By default, Hardware sets the fans to maximum speed as a Fail-Safe. When software is running properly, it periodically sets the fans to desired speed in a feedback loop based on measured temperatures. When the software is running normally, the fans operate in a sensible range based on temperatures.

When the software crashes or hangs, the cooling fan speeds do not get their periodic re-setting, and the fail-safe Hardware runs them up to maximum speed. So the fans running on high is a symptom, not a cause.

If you have not already done so, download this little non-invasive utility, run it, and post the results in a reply on the forums. No personally-identifiable information is included in the report. The utility was written by a trusted contributor to the forums, and uses only standard system calls to get its information. You do not even need to install it -- it can be run directly from the downloads folder and deleted immediately after use, if desired:

http://etrecheck.com

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That's the way I interpreted things. initially I suspected over heating in the graphics card, but a thorough cleaning of the heat-sink find etc resulted in no operational change. I have been used to expensive analytical instruments where each "unit" has sic (self indicating circuitry) so problems are easily narrowed down.

I have exactly the same problem. I have a macpro 3.1 OSX 10.11.6, every time I turn it on, right after I put my user password tries to show the desktop and it does not pass 10 seconds when the screen goes black and the fans start to sound very loud. Every time this happens I have to force the power off by pressing the power button for a few seconds until the computer turns off. Then I turn it on again and pass the same several times, black screen randomly, without being able to get the real cause. I've tried cleaning the computer physically, dusting, disconnecting all peripherals, disconnecting additional disks, changing graphics card, changing ram memories, reinstalling the system (I've tried all versions of Yosemite and all versions of The Captain) Without any success.

Does it work the same in Safe Mode? (hold down Shift at Startup).

Safe Mode loads a minimal set of extensions, including NO third-party extensions, and runs the display in Simple Mode, rather than the usual accelerated, interrupt driven mode. Screen redraw will be very slow.

Safe Mode does a disk repair as it starts up (which takes an extra five minutes) then demands you username and password, even if you normally auto-login. Safe Mode tries very hard NOT to use your settings, but to take the defaults for everything it possibly can, so sometimes the screen will be set to a default size and resolution. Changes you make in Safe Mode WILL "stick", so Safe Mode can be used to fix otherwise deadly errors such as setting screen resolution to a nonsense value (which would make the screen go blank).

HI,

it's a google chrome problem believe it or not, try clean install OS or window whatever that your using and never install google chrome ever. That will resolve the issue, at least my case. (Mac Pro 3.1 El Capitan Bootcamp window 7)

It may be related to hardware accel option that chrome has. (even if you install chrome and don't use chrome, chrome will still cause the problem. so, never install it on your system!) You may turn off the hardware accel option in chrome but I will just stay away from chrome although i really likeit. i am using firefox now, no issue at all. After long days of suffering from black screen and loud fan...now i am finally in peace.. thanks god.

Hi, i am sorry the problem was not the Chrome. After everal days, black screen and loud fan issue happened again....

I just gave up. I have tried thousand different ways to fix the problem.. sleepless nights and days. now I don't wanna waste my time on this stupid problem...have done enough. farewell to my 9 years old mac pro. you have served me well enough. hope you guys find a way to fix this..probably not by apple.. ( I kind of miss the Apple of Steve Jobs..I did not have single issue using my mac those days...after he passed away, so many problems using bootcamp. I think they are not pushing hard enough anymore)

Try to disconnect the front fan and the rear fan when your mac is down. Start without the fans and the problem is fixed. Stop the mac. Connect the fans and it's done. Worked for me. It seems my mac had overheated because I ran it without the cover. The motherboard seems to memorize an overheating. Unplug the fans resets this memory.

Hi. I have done as you suggested. Looking in the Diagnostic Reports folder reveals:-

How do you start up in Safe mode.

Hold shift at startup.

Try safe mode if your Mac doesn't finish starting up - Apple Support

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I had a similar problem. Old mac pro and randomly the monitors would go black.

Replying to this incase anyone else has this problem…

Tried all the restarts under the sun, reset the board only to get temporary fix. It got to the point where the monitors would black out repeatedly after a few minutes of resetting.

My final solution (May not work for everyone): Remove the graphics card and check to see if the copper fins in the heat sink are "caked in dust". On my ATI card i can see this from the bottom end. I took the hoover and placed it at the opening and the bit of the hoover nozzle that stuck out I covered that with my finger for maximum suction, I repeated this process from the opposite side where the air exits, after a few seconds the suction was enough to clean out the heat sink and the fan started to spin with the power of the suction.

I have replaced the card and now my mac is running very quiet for the first time in years. On removing the graphics card I noticed the bay was very hot including the card. I'm guessing the card cuts out to protect itself from overheating.

Don't forget to wear an anti-static wristband or discharge yourself first. Using a hoover was a drastic last step. Don't think an air duster would solve the problem as well as suction.

I Have a similar problem on my macpro 3.1 2008.

running 10.9.5 but i had the same problem under capitaN before I downgrade

The screens goes black silently and after few second all the fans start spinning high speed. At that point there is only force shutdown to do

TThe problem seemed to happen when I work on editing video or compositing in after effect, but it also occurr when running avast scan or backup data copying on exter al drive. So it seems to be independent from CPU or graphic load.

PPlus I had the same problem with 3 different gpu ( gtx570 Radeon 7950 and Radeon 2600xt ) the fact that It does the same with 2600xt makes me say it s not a power gpu matter because this card require very low power to run.

I Also unplugged every external drives, pcieusb3,0 card without progress.

I Ran reset pram smc hardware test (5hours ram test) everything stayed green.

SO so now I am thinking it could be osx problem OR power supply unit.

I Will try to remove all internal drive except osx and restart from 2dimm ram instead of 8 32gb

though this is exhausting and really **** me off if any of you get progress please post!!

CCheers

paul

look in the location mentioned in this article for any genuine KERNEL PANIC reports:

Mac OS X: How to log a kernel panic - Apple Support

Yes I have some kernel report in the few last days.

I also have powerstats diagnostic report and a system stats spin report at the exact time of a black screen + fan crash

How can I read and understand these report?

This is ironic,

but I am currently trying each pair os 4+4 gb dimm with very light config radeon 2600xt, and no more hard drives inside except os ssd.

The system is very stable, has been running After effect render on 8k video without any problem!!!

Better be a tortoise than hare ?