# Resolution problem on External Monitor



## jyx34 (Mar 25, 2007)

I'm trying to drive an external monitor from my laptop but it does not display correctly at the monitor's native resolution.

The external monitor is a 20" 1680 x 1050 ViewSonic. If I turn off the laptop screen and just display the external monitor I can see my desktop but it seems to think the native resolution of the monitor is 1024 x 768. The image is distorted at that resolution. 

If I change the Display Settings to 1680 x 1050 the desktop image is much larger than the screen. I don't understand how the laptop can support this resolution yet not "map" it properly onto the external monitor. 

Another strange symptom: The monitor has setting buttons on it that (presumably) work directly on the monitor (not through the computer). There is an "Informaiton" menu that lists the resolution. When the monitor is plugged into my desktop PC it lists the resolution as 1680x1050. When it is plugged into my laptop it lists the resolution as 1024x768. There is no way to change this setting directly on the monitor.

Is it a limitation of the laptop video chipset? If so, why can it display the desktop at 1680x1050, just not mapped correctly onto the monitor? And why 1024x768, which is less than the laptop screen?

Thanks for any help!
James

Hardware Details:
-----------------
External Monitor: 
ViewSonic VX2025vm 20" 1680x1050

Laptop:
Acer Aspire 5003WLMI
Windows XP Pro
AMD Turion 64 ML-32
15.4" WXGA Acer CrytalBrite TFT 1280x800 LCD screen
SiS760GX Display Adapter


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## TheMatt (May 9, 2006)

Hi James,

With that chipset, you have two options: Clone the display, or extend it so both monitors show half the desktop. You can't have two separate resolutions for each monitor unfortunately.

I am not sure what you mean about the desktop not being 'mapped correctly' on the screen.


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## Terrister (Apr 18, 2005)

The max display resolution for your video card is 1280 x 800.


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## TheMatt (May 9, 2006)

That card can get 2048 x 1536 @ 75 Hz, the max res on the monitor 1280 x 800 @ 60 Hz.

Go to Display Properties > Settings tab > Advanced... > SiS M760GX
You will see all display modes there.


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## jyx34 (Mar 25, 2007)

I basically have the same problem regardless of whether I extend the desktop across both monitors, try to mirror the desktop on each monitor, or turn off the notebook screen and just display the external monitor.

Your answer that the chipset just doesn't support two different resolutions on two screens seems right on. Regardless of which resolution I choose at least one screen shows a desktop image that is larger than the monitor, so I can only get to part of the desktop by moving the mouse off the edge of the screen, which causes it to scroll over and show the missing portion.

Interestingly, I upgraded the driver on the chipset and now it behaves a bit different. If I turn off the laptop screen (using fn-F5 key to tell it to show the external monitor only) and set the resolution to 1680x1050 it fills the whole external monitor without going off the screen. Almost exactly what I want (though still kinda fuzzy). Unfortunately when I detached the laptop from the external monitor it spontaneously rebooted the computer! Not good! I'm thinking it tried to apply that resolution to the laptop screen and it freaked out. Bummer.

At this point I'm willing to give up on this laptop with my widescreen monitor. Perhaps I should get a new laptop with a better graphics card. 

Here's a question:
If I want laptop with a small screen but want to dock it to an external monitor with a higher resolution and a different aspect ratio, are there laptops out there that can make this switch seamlessly (without rebooting or hassling with the settings)?


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## TheMatt (May 9, 2006)

It shouldn't reboot when you disconnect the monitor. Have you tried using the utility I described in my previous post to clone the display? If you do that, it shouldn't reboot when you disconnect the monitor. Also, you could use Fn+F5 to switch back to the laptop display before unplugging the monitor.


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## jyx34 (Mar 25, 2007)

Yes, I tried to use the display modes using the SiS controls. (On my computer it's under Display Properties > Settings tab > Advanced > Sis Utility Manager > Driver Mode Settings). This gives me the option of using a second monitor, and either extending the display or mirroring the display. Regardless of which setting or what resolution I choose both monitors come up with the image larger than the screen. It simply can't handle having the two monitors at different resolutions. 

The closest I can get is to use the fn-F5 to turn off the laptop monitor, which is the only way to get the image to display the correct size on the external monitor (and even then it was only possible after I upgraded the driver. If anyone is interested I upgraded to version 3.78 of the SiS driver, file uvga3_378.zip).

In todays testing it also rebooted just by pressing fn-F5, meaning I can't reliably change the display settings back and forth. That's one seriously screwed up computer. It really doesn't like having that external monitor plugged into it.


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## TheMatt (May 9, 2006)

I also upgraded the driver. The utility that Acer provides preinstalled with is outdated. 

You might want to try disabling automatic restart on system failure (press and hold F8 right after the Acer logo until the boot menu appears). Then post the entire message from the BSOD that appears.


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## jyx34 (Mar 25, 2007)

Ah, that's interesting.

<BSOD>
...
The problem seems to be caused by the following file: sisgrv
...

The device driver got stuck in an infinite loop. This usually indicates problem with the device itself or with the device driver programming the hardware incorrectly.

Please check with your hardware device vendor for any driver updates.

Technical information:
*** STOP: 0x000000EA (0x855299F0, 0x856A7E58, 0xF79D1CB4, 0x00000001)

sisgrv
Beginning dump of physical memory
...
</BSOD>

Unfortunately I couldn't find a more up-to-date driver (3.78 is from Feb 2007) so if it's a bad driver I don't know what driver to use.


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## TheMatt (May 9, 2006)

3.78 might be buggy. I use 3.79 with no problems.
http://www.sis.com/download/download_step1.php
Windows XP > IGP drivers > SiS 66x & 76x


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## jyx34 (Mar 25, 2007)

Well, Windows won't let me install the newer driver. It insists that driver is not better than the previous one, and I see no way to override it.

I found this faq entry that suggests my VBIOS may be the problem:
http://www.sis.com/support/support_faqs_4.htm

My BIOS version is listed as 2.27.g8, so that fits. They recommend getting 2.28 or later. 

Unfortunately, I don't know how to find the proper BIOS file to install. Any ideas?

Thanks!
James


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## TheMatt (May 9, 2006)

You shouldn't need to upgrade the VBIOS. Try uninstalling your current driver, then installing the new driver. Make sure you install it in Safe Mode (hold F8 at the acer logo untill the boot menu appears).


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## jyx34 (Mar 25, 2007)

Nope. Windows patently refuses to install the 3.79 driver, even after the old driver is uninstalled and I'm in safe mode. It says no suitable driver is found. I can reinstall the 3.78 driver.

Are you sure the BIOS isn't the problem? The faq seems to say my chipset requires the more recent BIOS to support high-resolution monitors, though they're talking about 1440x900 and I'm trying to run an even higher res monitor at the same aspect ratio: 1680x1050.
http://www.sis.com/support/support_faqs_4.htm


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## TheMatt (May 9, 2006)

I took a look. My laptop can easily do 1920 x 1080 on an HDTV that I hooked it up to. I have had no problems on any external monitors. That is just to support that resolution.

Try Driver Cleaner and see if it completely removes the other driver. If that still doesn't work, you might want to try the Acer display driver. If their driver has the same problem, then I suspect it is a hardware issue, and you should contact Acer support.
http://www.softpedia.com/get/Security/Secure-cleaning/Driver-Cleaner.shtml
http://global.acer.com/support/download.htm


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