Vista - Occasional Flicker in Dual-Monitor Mode

I have a particular problem:

The problem I'm having is this: In dual-monitor configuration, my one of my displays flickers once every few minutes. When it flickers, the flicker happens only on one or the other monitor, and never both monitors. My Samsung Syncmaster 226bw monitor's native resolution is 1680x1050, and the second monitor (Gateway FPD1500) is 1024x768. There is flickering on one monitor (one or the other monitor at a time), once every few minutes. In the flickering split-second, I see expanded, distorted text on the screen, like the text I was looking at exploded, then returned to normal display. There is otherwise nothing wrong with the display in either monitor. You have to have a fast, trained eye to catch that. Ever come across a problem like that?

I have determined that reduced blanking from my video card is in effect (pixel clock is at 119 MHz at 60 Hz vertical rate). This doesn't resolve anything, anyway, because at 1680x1050, the pixel clock is well below the max of about 165 MHz in standard blanking mode. (If you don't know what I'm on about, don't worry--I know it's a non-issue.)

The flickering seems to stop once the dual-monitor set-up is configured for single monitor display.

A possibility: the power supply is just barely providing enough power to drive the Visiontek X1300 XGE video card when in dual monitor mode. It provides only 300 watts. But it does meet the spec power requirements for the video card. And the card supports dual link DVI-I (two connectors), but both monitors only have single link DVI connectors. A single link DVI supports a max resolution of 1920x1200, which is enough for my dual-monitor set-up.

I downloaded PowerStrip 3.8, but adjusting the Horiz/Vert refresh rates didn't effect the anomaly.

I'm getting a new card, VisionTek HD 4670 with 1GB RAM and a new 400W power supply, Corsair,to replace the standard 300W PS. Both are from TigerDirect.

Right now I'm reading up on video card memory bandwidth ("memory width") and the marketing crap associated with those specs. Not that I think this has anything to do with my problem.

Anybody have any remarks?

it has to be a driver issue , probably related to the fact that your running at 2 differant resolutions , are both monitors working at the same frequency? are you running both DMT , could be a timing issue? im not familiar with ATI have you tried setting up custom resolutions at 59hz instead of 60 for example? and have you tried connecting with standard leads non DVI? if you run both monitors at 1280.1024 does the issue persist?

Very good question, didn't even think of that. I'm running both at 1024x768 now; we'll see what happens as time goes on. What is DMT?

I'll have to look at the driver thing, but I don't think that's the problem. But I'll check for an updated version.

Thanks for the reply.

The problem is fixed. I bought a used monitor (on ebay) the same size and the same model as my largest monitor, installed it, and there's been no more flickering for hours. They're both the same model: Samsung SyncMaster 226bw, and I'm surprised the price for a new one still hasn't dropped since two years ago when I bought the first one. Real popular monitor and well liked.

Funny thing: the VisionTek X1300 XGE video card didn't like the mixed size dual monitors even when I set the bigger monitor to the same resolution as the smaller one. Still flickered, though not as often.

I've never replaced the video card and didn't have to. I ran into problems with TigerDirect sending me the wrong card-- not once, but twice. I cancelled my order for a refund because I don't need it anymore.

I did replace the power supply with a 400 watter from Corsair, which did not, of course, alleviate the problem. Still glad I did it; it's a better PSU than the 300W Bestec PSU.

Problem solved, thanks for the help. Heh...