The highest contrast ratio of the S27A850 is 1000:1. That's 100% less contrast ratio than a 20000000:1 PC monitor, which is the most common contrast ratio. Across all LCD screens that were released more than two years ago the worst contrast ratio is Mega Contrast and the best is 100000000:1.
Alternative PC screens that have a 1000:1 dynamic contrast ratio currently available that you might want to look at include the Eizo ColorEdge CS230 (£426.99), or the Benq BL2710 (£336.53) which has a better Rating.
If you want a PC screen with a higher contrast ratio then you might also want to consider the DELL U2913WM (£324.50) (2000000:1 and higher rated); or the NEC MultiSync EA244WMI (£331.91) (25000:1 and cheaper), or the DELL U2713H (£371.00) (2000000:1 and cheaper).