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-   -   Horizontal and vertical refresh rate (

johannes 10-30-2003 06:17 AM

Horizontal and vertical refresh rate
Hi everybody!
After messing around with Debian on my machine for a while, I installed SuSE 8.1 on the notebook of my girlfriend (didn't want to configure all the exotic hardware there by hand :) ).
Everything is running fine, but there is one thing that drives me mad:
Suse configured the TFT-Monitor of the Notebook in such a way, that it ran with 70 hertz.
I've heard, that using TFT's with the wrong frequency can destroy them, and that the only refresh-rate allowed for most TFT's is 60 hertz.
To check which modes are supported, I booted windows, and the only mode supported there was indeed 60 hertz.
Now I tweaked the refresh rate myself (without really knowing what I was doing), and limited the horizontal refresh rate to 60 hertz.
The only mode with 60 hertz in sax2 is XGA, all other modes with 1024x768 use 70 hertz at least.
Therefore I chose XGA, and now it is running with 61 hertz (according to the sax2 test environment).
Can this marginal difference cause any damage to the TFT? What would happen if I would let the TFT work with 70 hertz?
Unfortunately, it is almost impossible to find useful information about this topic, I searched google for hours, and found nothing useful.
I have also tried to find some information in the manual, of course, but they aren't saying anything about the display's specs there...

I hope anyone can help me, because I don't want to destroy her notebook, it was hard enough to convince her that she should try Linux. :D

Best Regards,


BroX 10-30-2003 09:52 AM

Hi all,

I got a similar problem/question.

I am new as can be to Linux! Set up redhat 9 on a laptop yesterday (wow, even succesfully, with dual XP boot). Got a problem though with the LCD screen: it's flickering (small horizontal lines) when I change the resolution from default 800x600 to 1024x768.

BUT: it doesn't do that when I log on as root?!

I've been reading all kind of pages with all sorts of tips, but before I try them out: how easy is it to destroy/harm a TFT LCD screen? Or: what should I definately NOT do?

Some specifications:
Max. LCD Res: 800x600 SVGA, 1024x768 XVGA
Colors with max. res.: 32 bit true color depends on video memory (which is 8 MB)
LCD size: 13.3" XGA TFT
Videocontroler: intergrated in SIS chipset (SiS630 GUI Accelerator+3D)

Laptop: Topline Amicus 3200S, Celeron 667MHz, 192 MB RAM, 10 GB HDD.

All suggestions more then welcome!

Kind regards, Leon.

xexix 10-30-2003 11:58 PM

61Hz will not cause any problems for you. Just to be clear, XGA is 1024x768, and horizontal refresh rates need to be in the Khz, i assume you meant vertical refresh rate. You may want to check out /var/log/XFree86.0.log for info on the timings that it found. Using a correct combination of horizontal/vertical/pixel timings you may be able to get the best resolution with your hardware. You can use a modeline calculator to help you:

johannes 10-31-2003 06:44 AM

Thank you very much, this calculator is great!
Now I can also try to make better use of nvtv on my machine. :D

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