display problem

I upgraded a PC to Win98SE for a friend of mine a couple of months ago. This is a pentium 233 mmx, 64 megs, onboard Sis video chip.Everything was happy, it went well. Recently his display went to some diagonal lines. Looked like the images were diagonal too. k...so I boot to safe mode, delete video driver and monitor. Reboot to command prompt, run regscan, reboot, let windows autodetect and install video driver(from the cd that came with the motherboard) and monitor. No help. Next I reboot to safe mode. I move that graphics accellerator silder all the way down. This time I can reboot in normal windows but can only display 16 colors. I move the accellerator to the next notch and reboot. Now I get back all my color options. I move the accellerator up to the next notch and boom.. the display goes screwy agian. When I get the
accellerator back to the second notch(from the left) and won't let you move it to the right anymore. I'm sure that before the display problems the slider was all the way to the right. It works like this for now but I suspect there is still something wrong. Oh, I don't remember exactly when in this process I did this but I ran the system file checker, it found a corrupt file and asked for the 98 cd to replace it. I don't remember the name of the file but it was replaced. There are no games on this PC. The only SW loaded recently was Juno Internet SW. No new HW. That I know of. Will the slider being on the second notch affect performance? What could have caused these changes? What gives?
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Borrow a video-card, and plug it in.
The BIOS should then bypass the onboard video, and use the video-card.
If you still have problems, then it's your monitor, not a video-card problem.
Did the PC come with a diagnostic disk?  Many manufacturers include a hardware diagnostic program that you can run.  It is possible you have a flaky video board.  I have one computer that acts up like that.  Kick the computer and the video works again.  :)  (I'm only partially joking about kicking the computer.  Er, actually, I mean to say that I "manually adust the physical location of the internal components."  Yeah, that's it. <grin>  Don't kick you're friend's computer! LOL  But do do the following:)

Make sure the video card is in securely.  And see if the PC came with some hardware diagnostics and try to run those on the video card.  Sometimes the video card just "goes" and it's time to replace it.  Or sometimes it gets loose from moving the computer around and starts behaving irratically.

Also, make sure you have the most recent video driver.  Many times the drivers on the restore CD's are not the latest drivers.  Reason?  Many OEM's mass produce the restore CD's and actually install your computer with a Master CD instead.  Their master CD may have more recent drivers than the ones on the restore disk.

I doubt if its the monitor, but it wouldn't hurt to try it with a different monitor to see if the behavior is consistent.  It would be good if you could actually try a monitor by a different manufacturer just to see what would happen with a different driver installed.

But check the hardware first.  Your symptoms sound very similar to a video card problem I had recently.  It turned out to be a flaky card in my case.

Check for updated drivers too.  Sometimes older version have bugs that appear under certain situations.  An updated driver could solve the problem if it isn't a hardware problem.
Also, is the Accelerator slider the only option effected in the control panel, or are other options effected too?  For example, are there less resolution and color choices than there used to be?

If you start seeing that, then you probably have a video card or a monitor hardware problem.  When the video driver cannot access those features it makes them unavailable to you.  That usually indicates a hardware problem with the monitor or video card.
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have you tried :
a. setting the display adapter as one of the standard display types? this will identify it as a driver issue.
b. often the maker of the chipset makes a leaner and more stable driver than the oem, which usually includes a bunch of other unneeded fatware to confuse the issue.(ex I have a diamond viper 550, and since diamond drivers notoriously suck, I use nvidia's -the chipset maker-drivers. )
red10Author Commented:
Thanks for your answers. I'm looking for a more detailed account of what the acellerator slider does. I'd like to understand what happened not just fix it. I mean the PC is functional now.

Otta: I realize I can use another video card and try a different monitor. This may fix it but I still won't understand what went wrong.

Wistex: First it's an onboard video chip
not a card. The slider has four positions I can now only use the first two. In the first I get only 16 colors.
In the second position I get all the color options. Third and fourth position are no longer avavilable.

jcmf: The only other driver I can use is
Windows' own standard VGA. This limits me to 16 colors.

If I used this driver sucessfully for sevevral months why can't I use it now. Wouldn't something have to have changed. I know the video chip may have gone bad or maybe even the monitor.I guess I'd like a more detailed description of how windows uses the slider. What does each notch enable or disable etc. Why would windows grey out position three and four. They weren't greyed out before. Is there a reason why this may happen other than a bad video chip or monitor? BTW, bios reports using 2megs for video. I guess i'm not looking for a fix as much as information.

Thanks again for your help.

Red, it could be the chip on the motherboard, or it could be a heat problem, or even something such a refresh rate for the monitor. Here's some info for you. You may also have a problem with the refresh rates for the monitor.


Windows 98 Second Edition is compatible with Windows 95
display drivers. However, because the internal structure
and behavior of the operating system have changed since
Windows 95, some problems in existing Windows 95 drivers
might become apparent only in Windows 98 Second Edition.
If the Windows 98 Second Edition CD contains a driver for
your device, Windows 98 Second Edition automatically
upgrades known bad drivers (see Windows 95 Upgrades
section earlier in this document). If the Windows 98
Second Edition CD does not contain a driver for your
device, Windows 98 Second Edition converts the driver to
VGA to allow the system to start. In this case, you need
to obtain an updated driver, either by following the
procedure in the Windows Update or Windows Driver Library
section earlier in this document or by contacting your
display hardware manufacturer.
Windows 98 Second Edition Setup configures your adapter
type based on the controller it uses, for example, S3,
Cirrus Logic, or ATI. However, you may find a more exact
match for your adapter make and model by using the Update
Device Driver wizard.
In most cases, selecting a more precise adapter type
does not change the driver or its behavior in any way.
It only changes the name displayed in the Display
Properties dialog. If your system is working with the
display driver Windows 98 Second Edition automatically
installed, there's no need to make a change.
>>> To choose a more specific adapter:
1. Start the Update Device Driver wizard (see
   Changing device drivers in Windows Help).
2. Click Next.
3. Click Display a list of all of the drivers
   in a specific location.
4. In the Models list, select your adapter.
5. Click Next, and then follow the instructions
   that appear on your screen.
If Windows 98 Second Edition does not contain a
driver for your monitor type, select one of the
standard monitor types instead. This selection will
not adversely affect the performance or quality of
the Windows 98 Second Edition display output.
To adjust the refresh rate in Windows 98 Second
Edition, click Start, point to Settings, and then
click Control Panel. Double-click Display. Click
Settings, and then click Advanced. Click Adapter,
and then select a refresh rate from the list.
You must select a monitor in order to set refresh
rates. If Monitor is set to [unknown monitor], no
custom refresh rates are available.
Refresh rates are affected by the capabilities of
both the display adapter and the monitor. Windows 98
Second Edition makes available all the refresh rates
within the combined capabilities of the display
adapter and the monitor.
>>> If your display is visible but imaging incorrectly:
1. Right-click the desktop.
2. Click Properties.
3. In the Display Properties dialog box, click the
   Settings tab.
4. Click Advanced, and then click Performance.
5. Move the Hardware acceleration slider one notch
   to the left.
If the problem isn't corrected, repeat the above
procedure and move the slider farther to the left.
NOTE: Moving the Hardware acceleration slider to
the left disables some of the graphics acceleration
functions of your display adapter. If your display-related
problems are due to incompatibilities in the display
driver, this fixes them by using less of the
acceleration features in the driver.
>>> If your display is blank or unreadable when
    Windows starts:
1. Restart your computer.
2. Press and hold CTRL until the Microsoft
   Windows 98 Second Edition Startup menu appears.
3. Select Safe mode.
   Windows starts in VGA mode.
4. Right-click the desktop.
5. Click Properties.
6. In the Display Properties dialog box,
   click Settings.
7. Click OK.
   Windows notifies you that it will restart
   in VGA mode.
8. Click Yes, and restart your computer.
When your computer restarts, it will be running
in VGA (640x480, 16-color) mode. You can now reset
your display settings by right-clicking the
desktop, clicking Properties, and then clicking
Settings. If the resolution you want to select is
not available, choose another resolution (anything
but 640x480, 16-color), and let Windows restart.
The full set of resolutions and color depths will
be available after you restart your computer.
NOTE: Your display can be blank for a number of
reasons, including incorrectly set refresh rates,
an incompatible display driver, an invalid mode,
etc. Because the display is not visible in these
cases, it is impossible to correct these problems
without restarting in Safe Mode. In Safe Mode,
Windows does not load your original display driver,
so none of the display settings are available for
you to change. Instead, Windows automatically
resets your display settings to the defaults
(640x480, 16-color, single monitor, default
refresh rate). Then, you can restart in normal
Windows mode and make corrections to your
display settings.
After restarting your computer in Safe Mode,
change the resolution to VGA. Not all display
modes may appear in the Display Properties Settings
dialog box. This is because when Windows 98 Second
Edition is running in VGA mode, the accelerated
display driver is not loaded, so Windows cannot
query it for available modes. Once you switch to
another mode, Windows prompts you to restart so it
can load the accelerated display driver. After the
second restart, Windows 98 Second Edition adds the
full mode list supported by your display hardware
to the Display Properties Settings dialog box.
Although most programs allow you to dynamically
change color depth, some programs may not display
colors or other elements correctly after a color
change. To avoid this problem, change color depth
before you start the program. If you change color
depth while a program is running, you might need
to restart the program to ensure that the changed
setting works correctly.


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Since Dew mentioned heat, you might as well check for dust.  Dust will create irratic behavior in a computer too.
red10Author Commented:
Thanks everyone for your input.
You're quite welcome!
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