 The highest resolution modes were only used in special, opt-in cases rather than as standard, especially where high line counts were involved.Standard VGA monitors had a fixed line scan (H-scan) rate"multisync" monitors being, at the time, expensive exoticaand so the vertical/frame (V-scan) refresh rate had to be reduced in order to accommodate them, which increased visible flicker and thus eye strain.For example, the highest 800×600 mode, being otherwise based off the matching SVGA resolution (with 628 total lines), reduced the refresh rate from 60 Hz to about 50 Hz (and 832×624, the theoretical maximum resolution achievable with 256kb at 16 colors, would have reduced it to about 48 Hz, barely higher than the rate at which XGA monitors employed a double-frequency interlacing technique to mitigate full-frame flicker).