Kremmel, your ASUS monitor identifies itself as a PB287 from week 16 of 2014, model 28a2. I found an EDID from www.overclock.net for the PB287Q (week 20 of 2014 model 28a3).
The differences between EDID's of PB287 and PB287Q:
- The PB287Q has more Established and Standard timings defined. That probably doesn't matter since you can add any missing timing you want (and you probably don't want these timings).
- The timing for the 3840x2160 60 Hz mode is slightly different. The PB287 uses a pixel clock of 533.280 MHz to get an exact refresh of 60 Hz. But the PB287Q rounds that to the nearest quarter MHz (533.250 MHz) possibly because graphics cards are limited to quarter MHz increments? SwitchResX also uses quarter MHz increments for its calculations.
- The horizontal blanking is different. The PB287 has a horizontal sync width that is 56 pixels longer, with the horizontal back porch being 56 pixels narrower. The PB287Q uses CVT-RB values.
- The vertical blanking is different. The PB287 has a vertical front porch, sync width, back porch of 8, 10, 44 but the PB287Q uses CVT-RB values (3, 5, 54).
The PB287 and PB287Q use the same timing for 3840x2160 30 Hz but the timing is not CVT-RB or CVT or GTF. It appears to be closest to CVT-RB. They use a faster clock and longer blanking periods.
ASUS EDID: 297 MHz, H: 176,88,296 V: 8,10,72 (30 Hz)
CVT-RB: 262.75 MHz, H: 48,32,80 V:3,5,23 (29.981 Hz)
Very strange. Maybe the ASUS monitor would prefer a standard CVT-RB timing for 30 Hz? Try adding a custom timing with SwitchResX. I don't know if the OS X driver will use the custom timing or the EDID timing - if it doesn't work then you might need to removed the 30 Hz timing from the EDID to ensure that the custom timing is used. But if 60 Hz is working, then why would you want to try 30 Hz...
Differences between EDID's of Samsung U28D590 and ASUS PB287Q:
- The U28D590 says it supports 10 bits per primary color channel. PB287Q says 8 bits. Do you see a difference using "Billions of colors" instead of "Millions of colors"? In "Millions of colors" mode, try detecting a difference between color 50/255 and color 51/255. In Billions of colors, you can try detecting differences between color 50/255.75 and 50.25/255.75 and 50.50/255.75 and 50.75/255.75 and 51.00/255.75 (or multiple by 4 if #/1023 makes more sense). The difference in color is more easily detectable if they are drawn side by side with no space between.
- Image size physical dimensions: Asus: 621x341 mm, Samsung: 607x345 mm. I don't know of any software that cares about the physical dimensions. One or both of those values is wrong since pixels are supposed to be square on both displays and one has larger width and the other has larger height. Since the displays are 16:9 then the values would be Asus: 621x349.3 mm or 606.2x341 mm, U28D590: 607x341.4 cm or 613.3x345 cm.
- Different set of Established and Standard and Detailed timings. ASUS has some CEA timings specified, Samsung does not.
- Samsung specifies a 2560 x 1440 60 Hz detailed timing mode but ASUS specifies a 3840 x 2160 30 Hz detailed timing mode instead.
- ASUS range: Monitor ranges (CVT): 30-80Hz V, 24-160kHz H, max dot clock 600MHz; Samsung range: Monitor ranges (GTF): 56-75Hz V, 30-134kHz H, max dotclock 540MHz. GTF!? ***!? I think ASUS is more correct than Samsung here.
- ASUS supports 96 KHz audio, Samsung maxes out at 48 KHz.
- The ASUS has a HDMI data block specifying max TMDS clock of 600 MHz.
