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Old 05-14-2005, 10:33 PM   #1
Registered: Nov 2003
Distribution: Debian - Lenny
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Quick flash occasionally on the monitor

I occasionally see a quick flash of light on the monitor screen(ViewSonic). I don't know if its my monitor or my Video Card. To buy a Video Card would be the cheapest way to find out.
sudo lspci -v reveals
0000:01:00.0 VGA compatible controller: Silicon Integrated Systems [SiS] 65x/M650/740 PCI/AGP VGA Display Adapter (prog-if 00 [VGA])
Subsystem: Silicon Integrated Systems [SiS] 65x/M650/740 PCI/AGP VGA Display Adapter
Flags: 66MHz, medium devsel, IRQ 16
BIST result: 00
Memory at c0000000 (32-bit, prefetchable) [size=128M]
Memory at cd000000 (32-bit, non-prefetchable) [size=128K]
I/O ports at c000 [size=128]
Capabilities: [40] Power Management version 1
Capabilities: [50] AGP version 2.0
I went to in search of Sis Video cards.
What does 65x/M650/740 mean? If I knew I could better determine what card I should buy.
Old 05-15-2005, 04:12 AM   #2
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I went to in search of Sis Video cards.
What does 65x/M650/740 mean? If I knew I could better determine what card I should buy.
65x/M650/740 is the type of video card chipset you have. Perhaps it is built-in to the motherboard?

You do not need to get another SiS videocard. I would strongly recommend one made by NVIDIA, as they have very good linux drivers (search on this board, or go to

If you install a new video card, you will need to disable the on-board one in your BIOS.
Old 05-15-2005, 09:46 AM   #3
Registered: Apr 2005
Location: chained to my console.
Distribution: LFS 6.1
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this may sound like an odd question, but bear with me....

whats your screensaver?

with some of the screensavers i have used (namely the ones like spotlight that take a screengrab) there is a brief "flash" of the screen when the screensaver activates, from what i can tell its when the screensaver grabs a screenshot to use in its graphics. usually this "flash" of the screen only occurs when the screensaver is starting.

maybe someone might know what the flash is if you can tell us when it occurs, or if something causes it? if its a software thing that can be turned off (like my screensaver flashes) it will save a few quid instead of buying new hardware.
Old 05-15-2005, 01:38 PM   #4
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Have you checked to see if you've got your system configured for a "Visual Bell" or "Visual Console Bell"?
Many systems may be configured to have <Ctrl>-G trigger any combination of:
Visual Bell (usually a brief inversion of the framebuffer)
System Bell (usually the motherboard's beep device)
Audio Bell (usually a sound played through your sound system).
Old 05-15-2005, 04:09 PM   #5
Ron Cook
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The first step is to try a different monitor if you have one available. If you still see the occasional flash, the problem will be related to software (such as the screensaver item mentioned earlier) or other hardware.

The video subsystem likely is not the source of the symptom, although it *is* possible.

My guess is that you won't see the flash if you try a different monitor.

Is the flash accompanied by any noise: a 'snap', 'pop', 'fizz', 'hiss' ?
Do you hear a high-pitched 'whistle' while using the monitor ?
Does the monitor exhibit any other symptoms: low contrast, can't attain maximum brightness, problems with stability of the image, poor focus, as examples ?
Is the Viewsonic monitor located in a humid and / or dusty environment ?

We don't want to admit that we have too much dust in our computer areas but the high voltages in a monitor are wonderful attractors of dust. Dust is conductive and can cause or aggravate the symptoms of high-voltage arcing.

Unless you are qualified to do so never open a monitor for any reason.
Take the monitor to a professional service center; a good local TV-service shop should also be equipped to clean a monitor.

In the same vein, you might want to check the inside of the computer case and the surfaces of all the add-in cards. Dust can cause arcing and damage to the electronics.

Ron Cook
Old 05-15-2005, 11:17 PM   #6
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also try wiggling the video cable at the monitor end and the PC end. its not uncommon to develop a connection or minor break in a weak wire right at the ends where the cable is commonly bent at extreme angles. a quick color shift can also be a symton of a bad cable. A cable that is attached at the monitor end can still be fixed, but will require some soldering and either reading repair manuals for pinouts or some tediuos use of a multi-meter. Again, a computer or TV repair shop should be able to fix this for less than the cost of a new monitor.

If you are just looking for an excuse to get a new video card, get an nvidia anyway. I had a sis in my last pc and man it sucked, your system will feel faster with even a low end GeForce card.
Old 02-11-2006, 02:09 PM   #7
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Hello everyone,

I've also got a SiS 65x/M650/740 PCI/AGP VGA Display Adapter. I've been using a PCI GeForce card up until today, when I needed it for another project. When I switched back to using the builtin SiS display adapter, I suddenly started to get the lines across my display when I type. I've used my roommate's monitor, but it still does the same thing. I've tried both CRT's and LCD's with no change. I've heard that there is a problem with the drivers for the SIS display chips, but increasing the amount of 'shared video memory' with your computer's BIOS may help. Unfortunately there is one version of the chip that apparently ignores that setting.

fwiw, Check out for the following note:
"And please don't complain about "driver bugs" if you see "flashing lines" on the screen; these are the typical effects of a bandwidth problem and unavoidable - even the Windows driver can't do better. In such cases, reduce the resolution and/or refresh rate and/or color depth, or use one output (CRT1 or CRT2) only. Sorry, can't help it. There is no driver bug involved."

Good luck,


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