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BFG 7800 GT OC and Viewsonic VX924 "flicker issue"

Last response: in Graphics & Displays
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January 19, 2006 5:11:05 PM

Hi all,

Just completed my build a couple of days ago, and I am trying to iron out a few wrinkles...

I am using a BFG 7800 GT OC video card and a Viewsonic VX924 display. I am very happy with both products, but am having one issue. When I first boot my computer there are a series of horizontal lines that flicker across the screen... they are very thin lines that "flicker" randomly on the screen in random spots from top to bottom... this continues on through initial login. Once the system has been running for a while (like 10 - 15 minutes), the symptoms appear to go away, for instance I have never noticed this while say playing Doom 3 and do not see it now as I type this message.

I am using a Asus A8N-SLI Premium motherboard and a Antec Sonata II case with stock 450 watt PSU. I had to use the PCI-e power adapter that came with the BFG card, because the one built into the stock psu appeard to have 1 to many pins...

Also I am using a DVI dual link cable instead of the DVI single link cable that came with the monitor... I thought this would increase performance / quality, but now I am wondering if this is possible the cause of the problem.

Many thanks in Advance,
BigTech
January 19, 2006 6:52:27 PM

you need a better psu dude a 450 is not going to cut the mustard buddy. nothing lessor than something that has 32 amps on a 12 rail.
Antec use to lie about the output on the 12 volt rail it was discovered that they could only output 20 amps and they claimed on the specks to do 32. Buy a new psu nothing less than 550 or even a 600
January 19, 2006 7:27:53 PM

Quote:
Hi all,

Just completed my build a couple of days ago, and I am trying to iron out a few wrinkles...

I am using a BFG 7800 GT OC video card and a Viewsonic VX924 display. I am very happy with both products, but am having one issue. When I first boot my computer there are a series of horizontal lines that flicker across the screen... they are very thin lines that "flicker" randomly on the screen in random spots from top to bottom... this continues on through initial login. Once the system has been running for a while (like 10 - 15 minutes), the symptoms appear to go away, for instance I have never noticed this while say playing Doom 3 and do not see it now as I type this message.

I am using a Asus A8N-SLI Premium motherboard and a Antec Sonata II case with stock 450 watt PSU. I had to use the PCI-e power adapter that came with the BFG card, because the one built into the stock psu appeard to have 1 to many pins...

Also I am using a DVI dual link cable instead of the DVI single link cable that came with the monitor... I thought this would increase performance / quality, but now I am wondering if this is possible the cause of the problem.

Many thanks in Advance,
BigTech

It just sounds like image tearing. Using Vertical sync fixes that, but can slow down some games.
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January 19, 2006 7:54:50 PM

It must be some PSU issue...or maybe you've just forget to set your monitors refresh rate.
January 19, 2006 8:07:28 PM

It could be a PSU issue, but if it was id be inclined to think there would be other problems too. Antec makes good PSUs, and 450 should be plenty to supply that. The first thing I'd do is make sure all video and power connections are snug. You also commented on something about that different cable you are using, try the stock one because this sounds more like an issue with a connection, or a bad card altogether.
January 19, 2006 8:08:40 PM

You might have a problem with your monitor's EDID. I don't know if your Viewsonic uses the same firmware as Dell, but they are having lots of problems with their Flat Panels with Nvidia and ATI card. If it is the same issue, that "flickering issue" will get worse and it will start to blank out on you. One way to fix it for now is to switch it back to the VGA cable instead of using DVI. Do a search on google for "Dell EDID problems" to see if this is the same problem you are having.
January 20, 2006 12:35:56 AM

Did you by anychance follow up on the thg on psu testing all symptom's resemble psu also it is recommanded to use 550 above for sli
January 20, 2006 1:19:09 AM

Thanks for the posts. I've been troubleshooting this most of the night, tried different cables, different resolutions, etc... Lowering the resolution appeared to fix the problem and using a VGA cable appeared to fix the problem.

In the end I went into the nVIDIA display settings and told it to use dsplay adapter scaling instead of monitor scaling, and that appears to have fixed it... I am running with the stock DVI cable connected and 1280x1024 resolution without issue... hopefully it stays that way :) 

BTW I did contact BFG support, and they have some "calculator" and they seemed to think that my PSU should not be a problem... not sure how much stock to put in it... but I also do not know of any other way to test for PSU problems.

Thanks for the help,
BigTech
!