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View Full Version : VGA connection + large LCD = flickering?


tokamak
03-24-2007, 06:08 PM
I have a 15.4" 1680x1050 laptop, so I went out and bought a ViewSonic VG2230wm (same resolution) to use at home. The screen looks great (and huge!) and I am pleased, EXCEPT I have one wallpaper that has a sort of grey-to-charcoal gradient and I can definitely see the monitor flickering/refreshing there. I tried changing the refresh rate from the monitor's native 60 mhz, but that made it look horrible.

I'm thinking the problem may be that I'm using a VGA connection (laptop has no DVI). Could this be the case? I can't notice any flickering/refreshing any other time, just on this one particular color gradient -- my eyes usually aren't too sensitive to this kind of stuff.

BTW, I have been using this wallpaper on my laptop LCD and havent noticed this effect. Laptop graphics card is a discrete GeForce Go 6600 128mb. I'm thinking it's got to be either the VGA connection or a bad monitor. :(

BassBomb
03-24-2007, 09:21 PM
its the brightness of the monitor,

you arent used to the monitor ........ its an LCD and sometimes looks funky to new users (yes you have an lcd in your laptop, but its not the same thing)

you just will take some time getting used to it

if you can video tape it wiht a webcam, then maybe i can make sure its what im thinking of and not a faulty monitor

Matthias99
03-24-2007, 09:21 PM
I have one wallpaper that has a sort of grey-to-charcoal gradient and I can definitely see the monitor flickering/refreshing there.

You may be seeing interpolation from the screen. It's a 6bpp panel (rather than 8bpp). On certain shades, the pixels will be changing back and forth between two slightly different colors to approximate one in between.

dug777
03-24-2007, 09:30 PM
More likely to be an interpolation issue than a VGA connection issue, especially with a 6bit panel and a charcoal like colour....

VGA doesn't limit your refresh rate at that level...

tokamak
03-24-2007, 09:54 PM
I've now noticed that it actually happens with any dark, solid color. I only notice it when I'm, say, moving the mouse -- only when there's motion somewhere on the screen.

So basically I'm stuck with this because its a 6bit panel? I've used plenty of LCDs before and never noticed it (maybe they were 8bit panels). It's not a super-annoying, but I'd like to get rid of it if there's a way.

justlnluck
03-24-2007, 11:18 PM
Tokamak, this is getting interesting... First off, I own a Westinghouse 32w6 with a VGA connection and I never notice any flickering on any background colors, so I'm not sure VGA is the culprit. But, I was interested in purchasing an HP LP2065 LCD monitor. Supposedly it has an S-IPS panel (8-bit) and on www.dpreview.com, multiple forum members are complaining about flickering on gray backgrounds! I was so ready to buy that monitor. But those reports along with other reports that some people have problems with the one side of the monitor being dimmer than the other made me second guess. Hearing about your story makes me even more confused because your monitor uses a different LCD technology (TN 6-bit). Can you exchange it? I am curious now whether it's the individual monitor or if certain panels experience this. I hope it's the former, so you can get a good one...and I in the future!!

dug777
03-24-2007, 11:45 PM
Originally posted by: tokamak
I've now noticed that it actually happens with any dark, solid color. I only notice it when I'm, say, moving the mouse -- only when there's motion somewhere on the screen.

So basically I'm stuck with this because its a 6bit panel? I've used plenty of LCDs before and never noticed it (maybe they were 8bit panels). It's not a super-annoying, but I'd like to get rid of it if there's a way.

lol, have you installed your graphics drivers? latest ones?

Always worth a try :)

tokamak
03-25-2007, 01:24 AM
dug777, I just updated the drivers using www.laptopvideo2go.com (nvidia doesn't have drivers for the Go 6600 on their site). Doesn't seem to help any.

justinluck, I think I may try taking this thing back and getting a different one. I'm having a hell of a time finding anyone else with a similar problem via Google. I got it at Fry's, they should be willing to do a straight up exchange.

On a pure red (255,0,0), green, blue, white, etc background, the flickering doesn't happen. In fact, this thing is the bomb in normal use. But in any large black, dark grey, or dark colored areas, it's basically the same sort of thing you'd see if your CRT refresh rate was set too low. It's pretty subtle, but it's definitely there.

Either I don't understand interpolation correctly, or I don't think that's what's really going on. Even on pure black (255,255,255 in MSPaint), the flickering shows up -- I'd think even a 6-bit panel could do that without having to interpolate.

Thanks all for the suggestions so far.

justlnluck
03-25-2007, 03:43 AM
Tokamak, let me know if this link sends you to a discussion about the flickering. Is this what you are experiencing?

http://forums.dpreview.com/forums/readf...rum=1004&message=21536081&changemode=1 (http://forums.dpreview.com/forums/readflat.asp?forum=1004&message=21536081&changemode=1)

nullpointerus
03-25-2007, 07:49 AM
Originally posted by: tokamak
I have a 15.4" 1680x1050 laptop, so I went out and bought a ViewSonic VG2230wm (same resolution) to use at home. The screen looks great (and huge!) and I am pleased, EXCEPT I have one wallpaper that has a sort of grey-to-charcoal gradient and I can definitely see the monitor flickering/refreshing there. I tried changing the refresh rate from the monitor's native 60 mhz, but that made it look horrible.
I had the same problem with my old no-name 17" LCD via DVI-D. There's just something in that particular model that makes grays flicker. I believe it may have something to do with LCD panels having different color transition times and seeing the worst case gray-to-gray response times, but I'm no expert. Perhaps xtknight or videopho could tell you something more.

tokamak
03-25-2007, 01:22 PM
justinluck, the problem the are describing there seems similar to mine, but there are some distinct differences. First, mine doesnt start as the LCD warms up. In fact, I can see it happening when I first turn on the computer and its at the POST screen. Also, they all seem to feel like it goes away when they increase brightness and contrast -- on mine its almost the opposite, I don't notice it as much if I lower brightness and contrast, but when they're high its definitely there. Last, they all see it on medium colors, for me it only happens on very dark colors (black, charcoal, dark navy, etc.).

I'm going to try a different VGA cable and if that doesn't work go see about swapping this bad boy at Fry's. I'll report back.

tokamak
03-25-2007, 01:27 PM
also, I tried the clock/phasing test at http://www.techmind.org/lcd/ and at first it "crawled" vertically so I thought maybe the phasing was off. But I adjusted the monitor so that it stopped doing that but still get the same effect on black/dark backgrounds. :(

ZombieLobster
03-31-2007, 11:35 AM
I joined this forum specifically to comment on this issue because I'm having the exact same problem. I just got a Starlogic 20" Widescreen LCD that has a noticeable flicker (more like a rolling wave) over dark colors, including black. The native resolution is 1600x1050, but the flicker also happens at other resolutions with higher refresh rates. This starts happening right from POST, not after any warm-up. It is currently connected via VGA cable from a GeForce 6600GT; I'm going to try DVI, but after reading the posts at the link provided by justlnluck, I'm not confident that will help.

cubeless
03-31-2007, 12:09 PM
this is kind of hijacking the thread a bit, but i'm curious about the whole dvi vs analog on the lcd's...

what would the downside be of a 5ms viewsonic analog only lcd @ 1440x900 vs a unit that has dvi? i ask since i have a 17in 1280x1024 kds lcs that is analog only (must be 8 of 12ms refresh, it's a couple years old now) and it seems to perform quite well (no real smearing or anything) doing movies and games and such...

other than u need an adaptor for most new vid cards to go from the dvi outputs to an analog dsub...

i generally use the kds for a 2nd screen for my lappy... one odd thing is that my new dell d620 lappy seems to look worse on the kds than my old d600... maybe the thing has crummier 2ndary ramdac or something?

ZombieLobster
03-31-2007, 01:37 PM
Update: I just got a DVI cable from MicroCenter and the flicker is gone. Apparently there's an issue with the analog input; I know it's not a problem with the analog output on my video card because I switched to the DVI port on the card with an adapter and still had flicker. I didn't try card analog to monitor DVI, though. I may attempt that for kicks just to see what the results are.

To cubeless: I've seen plenty of analog LCD screens that didn't have any significant display problems, but based on this experience I would hesitate to rely on analog; the flicker was very noticeable and quite annoying. It seems to be a rather uncommon occurrence since I struggled to even find information online about it. I wonder if it's a design problem or something natural to screens with high native resolution. Either way, I personally wouldn't take the chance. But that's me, and someone else's opinion may certainly differ.

Noema
03-31-2007, 02:18 PM
I am curious...I have the exact same monitor. Maybe I could try out the same image to see how it looks via DVI. At any rate this could confirm or rule out the interpolation hypothesis, or whether this is caused by the analog connection.

So far I haven't noticed any flickering at all via DVI, though.

kmmatney
03-31-2007, 02:41 PM
I don't think its the VGA connections fault entirely. I'm a programmer, and I had a pretty bad flickering problem with a grey background. I had to change the background color to fix it. The problem only occured on monitors using analog display, but these same monitors looked fine running all other programs. The old background that caused a problem was a checkboard pattern of white and grey pixels. Do you get flickering with different background colors?

I don't knowwhy they don't make more laptops with DVI output - you can always use a SVI-VGA adapter to get VGA outpt if you need it.

Matthias99
03-31-2007, 03:48 PM
Originally posted by: kmmatney
I don't knowwhy they don't make more laptops with DVI output - you can always use a SVI-VGA adapter to get VGA outpt if you need it.

The "adapter" only works if it's a DVI-I port and it can actually output both DVI and VGA. This, of course, costs more than only having VGA output capability, since you either need another TDMS chip, or you need to integrate one into the onboard GPU.

unfalliblekrutch
03-31-2007, 07:20 PM
I have a 22" westinghouse LCD that worked fine on my ati 9800 using VGA output, but the 9800 died and I am temporarily using onboard Via S3 VGA to run it and I have that flickering/refreshing problem. I have no idea what causes it.

tokamak
04-01-2007, 01:25 AM
Update: Finally got around to taking the original monitor back to Fry's and got another one, same model. Same result, flickering on solid black/very dark colors. Either my local Fry's (Austin, TX) got a bad batch of these, or its a problem with the monitor and not one of the 200+ reviewers on Newegg has noticed it. I'd say the former is more likely.

ZombieLobster: that's an interesting find you've made. Maybe it really is an analog input issue. Unfortunately, my one and only computer is an Asus z71v laptop -- no DVI. I am afraid now that if I buy another 22" LCD, I will have the same problem because I can't support DVI.

Noema: If you want to try out a similar image to what I was having problems with, change your desktop wallpaper to solid black. Voila, that's it. Flickering/rolling/refreshing, whatever you want to call it. I noticed that it got especially bad when I grabbed a desktop icon and moved it around. I couldn't notice it on photos, games, web browsing, or basically anything that wasn't a large area of dark color/black.

CCityInstaller
04-01-2007, 10:31 AM
Originally posted by: tokamak
Update: Finally got around to taking the original monitor back to Fry's and got another one, same model. Same result, flickering on solid black/very dark colors. Either my local Fry's (Austin, TX) got a bad batch of these, or its a problem with the monitor and not one of the 200+ reviewers on Newegg has noticed it. I'd say the former is more likely.

ZombieLobster: that's an interesting find you've made. Maybe it really is an analog input issue. Unfortunately, my one and only computer is an Asus z71v laptop -- no DVI. I am afraid now that if I buy another 22" LCD, I will have the same problem because I can't support DVI.

Noema: If you want to try out a similar image to what I was having problems with, change your desktop wallpaper to solid black. Voila, that's it. Flickering/rolling/refreshing, whatever you want to call it. I noticed that it got especially bad when I grabbed a desktop icon and moved it around. I couldn't notice it on photos, games, web browsing, or basically anything that wasn't a large area of dark color/black.

Does your laptop happen to have an express card slot? If so then Belkin makes a hub that connects via EC and it will give you a DVI output. I am going to be picking one up shortly myself.

Noema
04-01-2007, 08:53 PM
Well, I tried a solid black background both via VGA and DVI and there was no flickering at all on my VG2230wm.

danylati
06-29-2007, 11:33 AM
now i see im not the only with this problem and this monitor VG2230WM, i have flicker in textures in some games like Flight simulator x or in displaymate in the test of full resolution / sharpness.

i tested the same monitor in the store and is the same or worst, i already tested a VG2030WM, this flicker too but not the textures, only when i enter a game or exit the game, this is resolved with power off and on the monitor.

my video card is a 2900xt, and me too if all put contrast to 100% in displaymate i have no flicker, but in FSX the flicker is there

xtknight
06-29-2007, 01:47 PM
Try the frctest (http://lcdresource.com/tools/frctest.exe)

My ViewSonic VP930b-2 has fairly obvious liney and swarmy-looking dithering, mostly around RGB(40,40,40) - RGB(70,70,70).

If it doesn't occur on any other colors then it's simply dithering. VGA isn't perfect either of course, and low bandwidth could cause lots of things. I did that test on DVI.

It could be that it's both FRC and VGA, especially since you see the flickering on a solid black.

Try VGA auto-sync/auto-adjust and see if that fixes it. If not, mess around with the phase/clock (or coarse/fine) VGA settings in the on-screen menu and see if that changes anything.

Also, laptop VGA connections are known to be very weak. Try lowering the display mode to 640x480@60 Hz and see if the flickering is less prevalent. If so, it may be your display adapter. That doesn't eliminate the possibility of a weak VGA converter in the LCD either, though.