For details on our color gamut testing and volume calculations, please click here.

Overall color accuracy is pretty good. We do see issues in the red and blue primaries, though. Red is under-saturated across the board, while blue becomes progressively more over-saturated as the level rises. It’s also a bit off in hue. The only compensation comes at the 100-percent point where blue’s luminance is lowered.

Calibration improves the results quite a bit. All of the luminance values are nearly spot-on and blue is still properly compensated at the 100-percent saturation point. Plus the hue errors are now almost non-existent for the secondary colors. To fix the remaining problems for blue and red would require a CMS. That’s not something one normally sees in a £400 monitor.
Now we return to the comparison group:

Color gamut accuracy is probably where calibration has the most impact. The average error goes from 2.93 to 1.83 Delta E. That may not seem like much, but if your application demands precision, it’s a worthwhile gain.
Gamut Volume: Adobe RGB 1998 And sRGB

The under-saturated red primary prevents the P2815Q from rendering 100 percent of the sRGB gamut. In most productivity or entertainment applications, this isn't a problem. However, photographers may want better performance in the gamut volume metric.
- Dell P2815Q 28-Inch Ultra HD Monitor Review
- Packaging, Physical Layout, And Accessories
- OSD Setup And Calibration Of The Dell P2815Q
- Results: Brightness And Contrast
- Results: Grayscale Tracking And Gamma Response
- Results: Color Gamut And Performance
- Results: Viewing Angles And Uniformity
- Dell P2815Q: 4K On The Cheap (With A Caveat)
To say Dell's customer service is bad would actually be a compliment to them. They have no means of repairing their monitors and do not supply service information to enable anyone else to repair them either.
Stay away from Dell unless you want a pile of junk and a headache to go with it.