Heavy Flickering even at 85Hz

[Sieg]

Hi,

I've been using Linux for quite a while now, but only on servers and on my laptop. For the first time, I've finally got it on my desktop, and therefore using X on a CRT monitor for the first time, but there seems to be an issue with the display. I've checked with xvidtune, and it says that my refresh rate is at 85Hz, under a resolution of 1280x1024. This is the same resolution and refresh rate that I use under Windows. The problem is that even at this resolution, I find that there seems to be very heavy flickering making it quite uncomfortable to the eyes. I can't see any similar flickering at this resolution under Windows. Does anyone have any idea what could be causing this and how to solve this?

Thanks a lot!

[Malakin]

Most monitors will display the current refresh rate in the onscreen menu, have you checked to see what the monitor says it's running at?

Maybe xvidtune can be wrong(?) Or maybe it's running interlaced.

[Sieg]

Hrm... Thanks, I'll check out the OSD when I get home tonight, somehow I had not thought about that

Where would I check for interlace though?

Thanks.

[meekjt]

If you want to make a mode line to your liking, try this out. http://xtiming.sourceforge.net/cgi-bin/xtiming.pl
After using this I have final been able to run my monitor to the max refresh, 110 Hz!! No more headaches. If you have more questions about how to get the mode line working in the config file let me know.

[Sieg]

Well, OSD shows the same, 85Hz.... I'll try another modeline. I had found a site that gave some and that's what I'm using, but this one might give better results. Thanks

[mooman]

The howto at the bottom of that xtimings page said that modelines are deprecated as of xfree86 4.0.X, and that those values are computed dynamically at startup.

Are you guys using older versions of Xfree or are they not telling the full story about still being able to manually set timings?

I'm just a little confused...
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Linux user off and on since circa 1995

[Sieg]

Honestly, the modelines have not worked But I thought it was just something wrong that I was doing. At least now I know that it was not me... hehe. Well, actually, they did change the behaviour, but they made it behave in the wrong way. I thought that the first page I had found just generated bad modelines, but I tried this morning with the new page, and instead I was starting in 1600x1200. So it's almost like it was working, just not properly at all. Problem is that outside of the weekend, I have VERY little time to try stuff at home, about 5-30 minutes max per night, so it has not been an extensive set of tests so far. Thanks for the heads up. I did notice a bit more flickering than before in my Windows too for a while, so maybe there's something wrong with my video card :\ I'll try a different one and see how it reacts.

[phong]

It may be that the refresh rate is just slightly different than Windows (like 85.2 instead of 84.6 or something) and everything's showing it to you rounded to the nearest integer. Something (the monitor, video card, local EM interference) is not liking a certain exact combination.

Also, on the question of modelines - sometimes they're useful still (but not all that often). For example, if you want to roll your own resolution (for example, I like to use 1400x1050 lately on my 19" because it's a nice middle ground between 1280x960 and 1600x1200, and still has a nice 4:3 ratio for square pixels), or if you need to adjust the position/size of the image and the controls on your monitor don't have enough range, you can do it with modelines (try out xvidtune).
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"An empty head is not really empty; it is stuffed with rubbish. Hence the difficulty of forcing anything into an empty head."
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[Pigeon]

[Malakin]

[Pigeon]

If I understand the original post, he dual boots Windows and Gentoo, and he has lots of flicker under linux at X resolution and Y refresh rate and no flicker in Windows at said rez/refresh. Odd problem indeed.