OS X 10.9.2 has been changed to break longstanding behavior with some 3rd-party displays. MPG doesn’t know how widespread the issue is among 3rd-party displays, but it definitely affects NEC displays (e.g., it might or might not affect Eizo or Dell or other brands).
Update March 10: The lightbulb clicks on—the 90° rotation appears to be an AMD thing, meaning AMD graphics and/or graphics drivers. Using the 2010 Mac Pro back in February, I noted a failure of the AMD Sapphire HD 7950 video card to function properly at 90° rotation even as the stock Radeon HD 5870 was working fine and worked fine for years. So the 90° rotation bug might be restricted to AMD graphics, but on any model Mac Pro.
MPG is working with Apple high level Support and also contacts at NEC to get this issue nailed down. Apple support has also communicated the issue to Apple engineers.
Any fix would likely go into 10.9.3 (now in beta), but MPG declines to access 10.9.3 beta, as the Apple NDA restrictions would preclude discussing it here.
UPDATE March 13: I am told that the issues are FIXED in the current 10.9.3 beta (not personally confirmed).
MPG has used the NEC wide-gamut displays for ~6 years now, most recently the 30" 2560 X 1600 NEC PA302W and NEC PA301W and also a 2560 X 1440 NEC PA271W (mainly as a spare on a 2nd system). All of them are highly recommended for their calibrated wide-gamut performance.
After years of functioning properly in a dual display setup, along comes OS X 10.9.2 and the 2013 Mac Pro. The following issues are extant*.
* These are issues that reasonable testing by Apple ought to catch (when code is changed, there is that testing thing to be done). OS X releases are breaking more and more things throughout the system at greater and greater frequency, not just display support.
Sleep mode broken by OS X 10.9.2
Various sleep behaviors no longer work correctly. MPG configures NEC displays like this for sleep mode.
Example, occurs with a single display or dual displays—
When the display is supposed to sleep after the Energy Saver duration specified, it ought to go blank (off). Instead with 10.9.2, the image on the display freezes, and remains at full brightness forever, the image burning itself in. Waking the machine up, normal operation resumes.
Since other users are reporting sleep issues with NEC displays on other Macs, this seems to be an OS X bug not involving the graphics card or Mac model.
Dual-display support with 90° rotation
The NEC displays are easily pivoted to be a portrait-orientation. MPG uses dual 30-inch displays, the main one in landscape orientation and the 2nd one in portrait orientation. This is about both desk space (and neck swivel capability) but also about workflow efficiency.
Substituting a 27" 2560 X 1440 NEC PA271W, portrait orientation works—sort of—reboots often force it to some lower scaled resolution while also swapping around the menu bar for good measure, forcing a redo to fix everything (which works ultimately). The flaky behavior strongly suggests a software bug (graphics drivers). And that is on two different Mac Pros (D300 and D700 models).
But the 30" display will not work at all at 90° rotation on the D700 GPU 2013 Mac Pro (after working for weeks on a D300 2013 Mac Pro, then beginning to fail after a swap between machines, suggesting a flaky graphics driver bug).
As it stands, one 30" display has now been rendered useless, costing me the better part of a frustrating day (including a call to Apple). Desk space and neck-swiveling make dual 30" displays side by side in landscape mode for both unusable for MPG. Having a $2200 investment idled is unfunny, but it is also an ongoing workflow impairment.
This 90° rotation bug appears to be limited to the 2013 Mac Pro seems; the same scenario worked flawlessly for the past ~4 years with NEC 30" displays on the 2010 Mac Pro.
AHA! The lightbulb clicks on—it might be an AMD thing, meaning AMD graphics and/or graphics drivers. Using the 2010 Mac Pro back in February, I noted a failure of the AMD Sapphire HD 7950 video card to function properly at 90° rotation (the stock Radeon HD 5870 was working fine and worked fine for years). So this 90° rotation bug might be restricted to AMD graphics.
Additional (non-NEC) graphics issues
The graphics drivers for OS X and the 2013 Mac Pro GPUs are prone to crash; crashes in Photoshop are still occurring with some filters. That display support (see above) has been multiply-broken makes sense in context.
These crashes started with the 2013 Mac Pro, and do not occur for MPG with other Macs running the identical tests.
The crashes have been partially addressed Adobe undid GPU support for fast sharpening, something MPG picked up on while retesting Photoshop CC speed on the 2013 Mac Pro yesterday.
Adobe has not weighed in on the remaining crashes, but to MPG it appears that Adobe code is not involved, e.g., that it is a bug in the Apple drivers for the AMD GPUs in the 2013 Mac Pro. It’s up to Adobe and Apple to publicly clarify the situation and the timeline for fixing it. MPG’s position is that silence on this and other such issues is unacceptable.