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Author Topic: Mac Pro 5,1 with MSI R9 280X - at a loss to explain this anomaly:-  (Read 506 times)

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« on: February 01, 2017, 01:35:36 PM »

Hello to all,

This is my first post here and I'd like to thank people for the helpful information I've found on this site.

I'd like to share the following with you in case someone can explain this 'anomaly' which I've spent nearly 3 weeks trying to resolve without success........ ( sorry its a bit wordy but felt it was important to convey the detail here).........

I have three essentially identical Mac Pro 5,1 machines - two are 'tagged' as 2010 machines and one as a 2012.

All have been upgraded to twin Hex core processors ( 2 x 3.06Ghz ) with 48Gb RAM and a Fusion Drive (250 SSD + 1Tb HDD).

All 3 have been fitted with identical MSI R9 280X Twin Frozr Gamer cards - all flashed with the switch in the 'Classic Bios' position using a ROM (MSIR9280X) found on this site.

Testing has been with a new iiYama 4K screen (SST) via a mDP to DP cable ( good quality cables).

Initially, running Yosemite, all 3 would boot, WITH boot screen, Monitor set to DP 1,1 to a Res of 3200 x 1800 (30Hz)

With monitor set to DP 1.2 all would 'hang' shortly after the chime - 'stuck' on a plain white screen, and require a reboot.

Upgrading the System to Sierra resulted in all 3 booting WITH boot screen showing ( monitor on DP1.1) to a 3840 x 2160 @ 30Hz screen

Manually switching the monitor at this stage (i.e. once booted) to DP 1.2 results in a display of 3840 x 2160 @60Hz.

ALL three WILL boot into 4K@60Hz......(monitor set to DP 1.2), IF I don't turn the monitor on until just after the chime.

Now the WEIRD bit..... at this point I discover that the 2012 machine just happily boots, with boot screen, straight into 4K@60Hz with the screen set at DP 1.2, waking the screen up as it starts i.e. just like a normal Mac setup.   The two 2010 machines will NOT do this !

In an attempt to find out why, I have systematically swapped almost all the components from the 2012 machine into a 2010 ( i.e. drive(s) with System / video card / processor board / RAM / etc ). None of this makes the 2010 machines boot into 4k@60Hz from 'cold' !.

The only components NOT swapped from the 2012 machine are the backplane and the case!  I note anyway that the Apple part number for the backplane board is the same for the 2010 / 2012 machines..... but have determined that the '2012' tag derives from the backplane board and not the processor tray...... so there must be 'some' slight difference?

Have checked the contents of the NVRAM but can find no obvious differences.

So....... after 2 weeks of endless searching / trial / error I still have three Mac Pros that happily boot, with boot screens to 4K@30Hz (DP 1.1 set), BUT a 2012 Mac Pro that also WILL also happily boot up straight into 4K@60Hz, (DP 1.2 set on monitor) with the normal boot screens.... whereas the two supposedly identical 2010 Mac pros won't do that.  The implication is that there IS something different about a 2012 Mac Pro, but from everything I know, have checked / researched...... there isn't supposed to be.

I'm now 'stumped', but if any knowledgable soul out there has any ideas why this 2012 Mac Pro is doing what it supposedly shouldn't be able to do (from what I've read on this site) and why or how its different from a 2010 models I would LOVE to hear from you !

Best Regards, and thanks for all the help on this site.

John H

( Oh!.... just for completeness, all the MSI cards have had the R17 resistor removed, report correctly in the System Info, and show as 5.0Gt/s)

« Last Edit: February 01, 2017, 01:46:08 PM by spirochete » Logged

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« Reply #1 on: February 01, 2017, 03:01:21 PM »

Interesting stuff, I had to speak to Apple support in the UK last week as my 2009 machine was dying. The support rep who was very helpful told me to get one of the 2012 machines as they are still supported by Apple.

Maybe there is a software check to enable this only for the 2012 machine?

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« Reply #2 on: February 01, 2017, 03:32:51 PM »

That did cross my mind.....

The ability to Boot into 4K@60hz (DP 1.2) happened on the 2012 machine as a consequence of applying the Sierra upgrade over a Yosemite setup.  This same process did not have the same effect on the 2010 machines.

Taking the boot drive out of the 2012 cMP and putting it in the 2010 cMP does NOT enable the 2010 to boot via DP1.2 - it hangs as before.

Left me wondering whether there is something in the 2012 machine's 'ID' that enables system functionality that doesn't occur with the 2010s?

Interestingly, this 'ability' is initiated (or not), almost immediately after the chime - so very little System software loaded at that point (if any).

DID however notice that resetting the PRAM (NVRAM) on the 2012 machine STOPPED it being able to boot into 4k@60Hz... it could only manage 4K@30Hz (like the 2010s) !!......had to restore it from its TM backup to get the 4K@60Hz functionality back......

The clue to what's going on seems to be embedded somewhere in the above.


John H

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