A note about VGAs and anything based off the VESA DB-15 video connector on the PCs. The higher the frequency used in SVGA and above aren’t strictly supported. While you might get an image, you’ll suffer focus (clarity of the image) and other weird anomalies will start to show up, if they’re not upfront and center. The display drive circuit, along with the DACs for in use with SVGA at that resolution and color depth may not be stable or able to correctly drive at that resolution, let alone color depth.
If you’re computer has as DVI-D connector and your monitor also has one, get a cable for it and plug it in, it will look a lot more sharp, your problems should also go away.
Note this is what can be achieved by the DB-15 monitor connection along sans the limitation of your drive circuitry of the computer and DAC frequency:
(Video Graphics Array) VGA 640 x 480
(Super Video Graphics Array) SVGA 800 x 600
(High Definition Television 720i/p) HDTV 1280 x 720
(Extended Graphics Array) XGA 1024 x 768
(Wide Extended Graphics Array) WXGA 1366 x 768
(Super Extended Graphics Array) SXGA 1280 x 1024
(Super Extended Graphics Array+) SXGA+ 1400 x 1050
(Wide Super Extended Graphics Array) WSXGA 1600 x 1024
(Wide Super Extended Graphics Array+) WSXGA+ 1680 x 1050
(High Definition Television 1080i/p) HDTV 1920 x 1080
(Ultra Extended Graphics Array) UXGA 1600 x 1200
(Wide Ultra Extended Graphics Array) WUXGA 1920 x 1200
(Quad Extended Graphics Array) QXGA 2048 x 1536
(Quad Super Extended Graphics Array) QSXGA 2560 x 2048
(Wide Quad Super Extended Graphics Array) WQSXGA 3200 x 2048
(Quad Ultra Extended Graphics Array) QUXGA 3200 x 2400
(Wide Quad Ultra Extended Graphics Array) WQUXGA 3840 x 2400
(Hex Super Extended Graphics Array) HSXGA 5120 x 4096
(Wide Hex Super Extended Graphics Array) WHSXGA 6400 x 4096
(Hex Ultra Extended Graphics Array) HUXGA 6400 x 4800
(Wide Hex Ultra Extended Graphics Array) WHUXGA 7680 x 4800
It appears you’re attempting to use the, “(Wide Ultra Extended Graphics Array) WUXGA 1920 x 1200” standard on your monitor. What you need to do is find out what refresh rates your monitor can handle at this frequency and what refresh rates your card are compatible with. Once you know, pick the lowest one first, then step up to the next, keep going until you get the weird effects. If you get the weird effects on one, test all of them. Pick the one that was least irritating or good and go with that. The DACs aka Digital to Analog converters actually have sweet spots in operation at specific resolution and color depths. It will be different per DAC so playing around with it will help you a great deal.
It’s also a possibility that your monitor while it is advertised that it can do it, it may not do it well. Stick with digital signals if you can. You’re eyes will thank you for it later.