Screen flickering/shaking @ 75hz (1 Viewer)

[Martin Fontaine]

For some reason, whenever I set my refresh rate to 70 or 75hz (Regardless of Resolution, from 640x480 to 1600x1200) the screen flickers and shakes a little. But at 60hz everything is fine (Other than the fact that having a refresh rate in sync with the room's lighting hurts the eyes)

I'm using a Viewsonic G810 21" screen with a ATI XPert 128 16 Megs (PCI) under Windows XP with the WinXP drivers from ATI.

I just tested switching back to 1152x864 @ 85hz and it's fine but on a 21" screen, I'd rather use a higher res.

Is there a reason why it does that only at those refresh rates? And what's the cheapest way to fix it (Is it a VGA Cable shielding problem or something)?

 

[Scott L]

Is your monitor close to a TV? Mine is and I have to keep it at 60Hz or else flickering lines rise up vertically.

 

[Gordon Moore]

Do you have anything else on the same circuit? I know at my place when the dehumidifier kicked on, it generated an annoying flicker in my monitor. I moved the dehumidifier to a different plug and problem solved. Check if it happens when the fridge kicks on ir something. Track down everything on the panel so that you know what's service by that circuit.

 

[Martin Fontaine]

I live in an appartment so I don't have much control on the circuits.

I tried using a different outlet (Not the power bar, straight into the wall) no effect. I went to Future Shop and bought a Power Bar that supposedly isolates from any interferences and made no effect (Got a refund the next day)

Would a UPS solve my problem? FS has one for 80$... It may not last that long on battery but I'm looking for clean power if that is the problem.

As for proximity with other devices, there's my computer speakers next to it, another computer with it's monitor close but it's off so it's not that.

 

[Gordon Moore]

A UPS with line filtering might be the order of the day. APC and others offer that feature. Another apartment may have a device that's junking up the line. Have you ruled out the monitor as being a problem? Have you tried it on a friends computer at the desired resolution and refresh? Conversely, have you tried a friends monitor at your place? If another monitor experiences the same problem then you know it's either your AC or the graphics card. Make sure all your components are up to snuff.

 

[Vince Maskeeper]

Have you checked the compatibility of your monitor to that refresh? Some displays have problems with specific resolutions at certain refresh rates (the Dell monitor I'm on now will not do 75hz cleanly, regardless of resolution).

-vince

 

[Gordon Moore]

From Viewsonics site...1600x1200 optimal resolution at 77Hz flicker-free refresh rate ...

Sounds like the ATI can't quite hit 77Hz or can it ...I guess check the literature...

77 seems like a strange number...

 

[Martin Fontaine]

I've tried putting the screen on the floor as far away from the computer as possible and plugged it in an outlet that is on a different circuit (I think) using an extension cord. So it's not proximity with other devices.

As for UPS, I'm looking into the CyberPower 700AVR which is not too expensive. Would this do? As for filtering, don't UPSes run the computer from the battery at all times and just constantly recharge the battery if there is electricity coming from the wall?

I'll just make sure I can return it if it doesn't help.

I'll ask my neighbor (Who'a also the manager/janitor of this appartment building) if he knows how the building is wired, maybe testing the screen on his PC would rule out my computer/power system.

 

[Gordon Moore]

Battery backup is just that...backup. If you set the voltage sensitivity on your ups too high, any really insignificant change in voltage will kick the ups over battery, till the voltage levels out (you have to have it set pretty high for this to happen and not all ups's allow you to adjust the sensitivity). 99% of the time you will be running off of line AC almost never off your battery. It sits idly by waiting for the power to shut off...the advantage is that you can shut your system down gracefully and save any work you may have open. The better UPS's will actively filter the line AC...most el' cheapo models won't and simply provide you with insurance during a power failure.

 

[Martin Fontaine]

Ok, I know all the advantages of being able to properly shut down on a black-out but considering black outs occur so rarely, it's not the most important for now. Even if it runs from the AC Line, does that still isolate from all interferences that could cause my problem? The unit I'm interested in is the CyberPower 700AVR will it actually fix my problem unlike the AR-7 that I tried?
So was that thing (The AR-7) supposed to fix my problem in the first place? (Assuming it really is a power issue)

 

[Gordon Moore]

One question...did you try 1600X1200 at 77Hz? As odd a number that is... Are your monitor timings loaded into XP?
try
http://www.viewsonic.com/drivers/vs_winxp.exe
About the Cyberpower at 149.00 is not a bad deal (assuming you were at FutureShop). They have another AVR for $99.00 made by (I forget the name it had something like Energizer on the box...but it had AVR as well). It's really hard to say how well it would help...Future's got a liberal return policy, I'd say try it and let us know Definately get the voltage regulator...I'm not sure if the filter on the AR-7 would similar or in the same league as to what's on-board a UPS...I doubt it but you never know. The nice thing about the software with a UPS is that if it "senses" the AC getting really crappy, it'll flip over to battery and it's completely transparent.

 

[TerryS]

I had this problem last year in my townhome. It would flicker and shimmer all the way until 100hz. Turns out I had my desk on an exterior wall and the incoming power panel for the building was right on the other side of the wall. I finally figured this out when I moved my monitor to the other side of the building. I never bothered trying a power conditioner as setting 100hz was easier.