Custom Resolution Utility (CRU)

[falkentyne]

ToastyX:

Sorry if this was asked before, but what exactly is the difference between driver "Default" timings and CRU default timings that have a lower HT and porch values?

Example: (at least on AMD) in windows,

The default timings for 1920x1080 for the Benq XL2720Z / 2420Z/2411Z are:

front porch 88 pixels, 4 lines
Sync width 44 pixels, 5 lines
Horizontal 2220, Vertical 1125.

Yet CRU uses these defaults for lightboost mode, for example:
front porch 48,3
sync width 32,5
Horizontal: 2080
VT (1138,1143 or 1149 for 100, 110 and 120hz lightboost).

Using the higher values works fine also without a problem for normal lightboost

However over a DISPLAYPORT connection, strange things start happening at a few specific custom refresh rates.

Certain specific custom resolutions / timings with the 2200 HT and 88 front porch timings will simply make the monitor shut off over displayport only, but not over DVI !

Some examples from my XL2720Z:

60hz lightboost (double strobe; just a curiousity):
2200 HT, 1155 VT, 60hz (this activates 60hz lightboost at 120hz strobe pulses on my XL2720Z, so it strobes twice per refresh)
Front porch 88/4
sync width 44/5

(note this does not work on the Asus VG248QE ! You need VT 1179 to get 60hz lightboost)

Displayport: monitor shuts off instantly.
DVI: no problem.

2080 HT, 48/3 front, 32/5 sync, 60hz, 1155 VT
Displayport: no problem.

50hz (custom resolution and VT required to enable benq blur reduction at 50hz with single strobe enabled; monitor will NOT strobe at all at default 50hz anything):

front porch 88/4, sync 44/5
HT 2200, VT 1360, 1920x1080@50hz

Displayport: monitor shuts off
DVI: works fine.

Front porch 48/3, sync 32/5
HT 2080, VT 1360, 50hz
no problem on DP, DVI.

Note: higher refresh rates like 100hz, 120hz, 85hz, etc work fine with the 2200 HT, etc and VT 1500.