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Horizontal and Vertical Display Frequencies Not Matching

Last response: in Graphics & Displays
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October 20, 2012 6:20:52 PM

Since day one my rig has had some issues with chopping. At first I thought it was faulty driver software for my dual Radeon HD 7770's but I have ruled that out, thought it was a poor quality HDMI cable (which it could have been) but now I'm using DVI which has removed about 90% of the chopping from cutscenes and gaming.

I have looked through all of the settings on my display and the video card software and I have come to the conclusion that the chopping is happening because my vertical and horizontal frequencies are not the same, I only get horizontal chopping. I have done some extensive googling and haven't been able to find anything that has helped.

Horizontal Frequency: 67.5
Vertical Frequency: 60.0


I don't know if the vertical and horizontal frequencies are supposed to be different but I am assuming they're the vertical and horizontal refresh rates and I don't understand why they're different. It's incredibly annoying and puts a hindrance on single player and multiplayer gaming.

Some help with this issue would be marvelous. Thanks in advance.

Here's some information about my setup and if more is needed just let me know.

Displays: Sceptre x270w-1080p (DVI) drivers are installed
LG L227W (HDMI to DVI adapter)

Video Card: CrossfireX AMD Radeon HD 7770 XFX (Dual obviously)

CPU: AMD FX 8150

16GB RAM

Windows 7 Home Premium x64
October 20, 2012 7:01:41 PM

Well, I'm no displays expert, but a 1920x1080 monitor with a horizontal scanning frequency of 67.5 kilohertz has a refresh rate of 60. You can find the equation for calculating this here: http://en.wikipedia.org/wiki/Horizontal_scan_rate

I was under the impression that horizontal scanning rate was something that applied to CRT monitors (since they actually have a moving electron beam), but like I said I'm no expert.

Could you better describe the "horizontal chopping"? It sounds to me like screen tearing which can be alleviated by enabling vertical-sync. Are you using v-sync?
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October 20, 2012 8:06:08 PM

larkspur said:
Well, I'm no displays expert, but a 1920x1080 monitor with a horizontal scanning frequency of 67.5 kilohertz has a refresh rate of 60. You can find the equation for calculating this here: http://en.wikipedia.org/wiki/Horizontal_scan_rate

I was under the impression that horizontal scanning rate was something that applied to CRT monitors (since they actually have a moving electron beam), but like I said I'm no expert.

Could you better describe the "horizontal chopping"? It sounds to me like screen tearing which can be alleviated by enabling vertical-sync. Are you using v-sync?


That makes some since. For every vertical refresh, there are 1080 horizontal refreshes (one for each horizontal line).

A kilohert is 1000 hz. So 60 * 1080 = 65.8 kilohertz. The slight difference could be to allow enough time for it to reset for the next horizontal line.
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October 20, 2012 8:18:44 PM

larkspur said:
Well, I'm no displays expert, but a 1920x1080 monitor with a horizontal scanning frequency of 67.5 kilohertz has a refresh rate of 60. You can find the equation for calculating this here: http://en.wikipedia.org/wiki/Horizontal_scan_rate

I was under the impression that horizontal scanning rate was something that applied to CRT monitors (since they actually have a moving electron beam), but like I said I'm no expert.

Could you better describe the "horizontal chopping"? It sounds to me like screen tearing which can be alleviated by enabling vertical-sync. Are you using v-sync?


I have tried vertical sync and it makes things much worse.

Here's a video I just took, please excuse everything going on in the background. Feel free to jump to the 30 second mark, if I knew a way to describe what's going on I would most certainly use words rather than recording it with my S3.

https://www.dropbox.com/s/0rxmw2tzgaifwcf/20121020_1504...

And I promise you it's not the recording device causing the issue.
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October 23, 2012 5:35:15 AM

I'm going to contact Sceptre and see if they have a solution if they don't then it's AMD.
Thanks for the help.
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