3rd monitor (thru dp) on XFX HD6850 flickering randomly


Feb 4, 2011
Hello all. I really need some help from you guys.

I have three 24inch monitor setup on my I5 sandybridge/XFX HD6850/8gigDDR3 (windows 7 ultimate).

First two monitor works perfectly fine. (phillips 240SW thru DVI and Samsung BX2431 thru HDMI -> DVI)

But when I got Benq BL2400PU connected thru display port cable, this monitor flickers at random time/frequency. And this is sort of Noise like flickering...
(sometimes on avg of once per hour ~ sometimes on avg of 30 times per hour)

I tried the following so far without success.
- Tried different display port cable
- Tried to set Benq as main, 2nd, or 3rd monitor in extended desktop
- Tried using it in Eyefinity setting instead of extended desktop
- Turned off every environment save, screensave related functionality
- Updated CCC to the latest version
- Installed monitor driver even though it shouldn't be needed in windows 7.

I originally suspected monitor being defect but the reason I am posting this article now is because this monitor seems fine on my test thru D-sub (1 monitor setting) even though test was not more than an hour... Also, I recently created another user account on windows 7 and when I log into that account, this monitor flickers like MADNESS (nearly every second) possibly because this account setting doesn't have CCC installed.

Since then, I tried to overclock GPU to various value from 775~850MHZ, Memory clock to 1000~1200MHZ, making sure temperature remains below low 60 or lower. I am still in the process of mindlessly trying different combination.

Can somebody give two cents on what else to try?




Apr 19, 2010
Its your overclock. if you leave your card overclocked, ALL of your digital signals will flicker. Mine does the same, turn off the overclock in CCC, the throttling the card does in the bios for voltages and clocks causes this

also, flash will cause flickering too

i have a 6870 (5870 cypress rebadge)

try using ONLY your VGA signal - unplug the DVI - bet it stops EVEN WITH your overclocks - something about SOME radeon cards VGA + DVI - im running 3 monitors off one card, an active VGA on display port - a HDMI > DVI converter > and my DVI signal, both my HDMI and DVI will flicker, my DP to VGA will not, because its being picked up as an analog signal