added a second monitor now text looks garbled when scrolling

[sathyan]

I added a 24" (1080p via DVI) monitor to my 22" (1680x1050 via DSUB) and set for expanding the desktop. When I scroll web pages (on either monitor), the text looks scrambled for about a second until it redraws. This forum site is a good example of the behavior. Unfortunately, I was unable to do a screen shot of it (redrew the text by that time).

The 22" monitor's DVI input is broken so I have to use analog in for it.

Is there a settings/configuration fix I need to do?
Do I need a CPU upgrade?
GPU upgrade?
This machine is not used for gaming just webpages, programming (Python, PHP, and SQL), and office (Word and Excel mainly).

system is:
Windows 7 Pro x64 SP1
Mobo: Gigabyte GA-MA790XT-UD4P
Chipset: AMD 790X
Socket: AM3
CPU: AMD Athlon II x3 435 (2.9GHz)
RAM: 12GB DDR3
GPU: HIS Radeon HD 4650 1GB
HDD: Samsung 840 SATAII SSD
PSU: Antec EA-500

 

[wirednuts]

possibly because youre using vga input maybe?

but more likely, your video card just cant handle it. I mean, I would think that card could... but who knows. have you tried lowering resolution to see if that helps? just to see if it does....

normally, spanning screens like that is handled by the gpu

 

[piasabird]

Maybe it is just video processing lag. Are you overclocking? Is the video card overheating? What if you turn one monitor off? Could make a difference which monitor is the primary monitor or if you reduce the settings. Maybe check out a Driver Update for dual monitors.

 

[Ravynmagi]

I might start with updating or reinstalling the video drivers.

 

[sathyan]

Running everything at stock speeds and temps are within parameters.
The issue occurs on both monitors regardless of which is primary. Tried switching primary monitor setting. Turning a monitor off does not fix it.
Going to look at drivers next. I have been using the one from Windows Update.

 

[mfenn]

What happens if you unplug the new monitor (from the computer)? Does it still give you trouble?

 

[Raduque]

I'd normally chalk that up to a bad VGA cable, but it does it on both monitors. Maybe a bandwidth issue? Are you using a DVI>VGA adaptor?