Hi all,

I've just realised that in games, my computer is displaying lots of weird, semi-transparent lines scrolling down the screen. It happens with other screens too, so it's not a screen issue. The reason I didn't notice before is that it's so subtle in lit areas that I took it for a post-processing effect, but having just tried to play a game consisting of mostly darkness, I've realised that the lines are much more prominent in darker areas and definitely shouldn't be there. I've rolled back my modest overclocks, and I've tried forcing Vsync both on and off, but to no avail, and the lines don't look like screen tearing anyway.

Current thinking, based on brief Google session, is that the problem lies with the VGA cable I'm using to connect the card to the screen. It goes HD7850 -> DVI-to-VGA adapter -> VGA cable -> screen VGA input. Google tells me that the VGA cable might be picking up interference from something, and that a (digital) DVI cable might fix this. Thing is, I used the same cable on my old PC and had no problems, so I'm not convinced. Temperatures seem fine, and my PSU should be more than capable of running this setup, so the only other option I can think of is a dying graphics card.

The lines don't show up on a screenshot and I don't have a decent enough camera to photograph them. Truth be told, a video would be best since they're only really noticeable because they move, but I don't have a decent video camera either.

I'm thinking:

i) Order a DVI cable, which will take a few days to get here.
ii) In the meantime, try an old graphics card if I can find one and see if the problem persists.
iii) Try different drivers? Seems odd that drivers could cause this behaviour in a variety of games/benchmarks, old and new. I think I'm running Cat 12.4s, which were the latest when I built this system.

Any other advice?

Thanks,
Steven

i got same prob,hdmi to hmdi is fine, so is dvi to hdmi,, but dvi to vga,has flicking scolling,

http://forums.overclockers.co.uk/showthread.php?p=21968212
seems may just need a bios update on the gpu,not try that yet.

driver changes did nothing, nor did playing with cc settings,

Thanks for the reply. The problem in the thread you linked to it a bit different from mine, particularly since mine only happens during games (as far as I can tell) rather than during Windows in 2D mode, but interesting nonetheless. Googled results say that perhaps this is due to the computer drawing more power in 3D, resulting in more interference. I've no idea how true this may be.

Anyway, new DVI cable ordered, will just have to wait and see if it fixes things. I'm still tempted to test an old HD2900, but I don't really want to take apart my system for no real reason.

:edit:

I've just tested, if I run Heaven in windowed mode, then I get the lines all over the entire screen and not just in the Heaven window itself. Also consistent with it being interference from a bad cable, but any other suggestions?

Okay, further testing done and I'm back to being puzzled. I don't have the DVI cable yet, but I've done some messing with the clock speeds and voltages of the card, specifically trying to underclock and undervolt.

At 500 core, 500 mem, -10% power, the lines are all but gone.
At 600 core, 500 mem, -10% power, the lines are back.
At 500/500 at standard power, the lines are faint but there.
At standard or overclocked speeds, at standard or higher voltage, the lines are worse.

Colour me confused. Here's hoping I don't need to RMA.

any luck mate

sjt269 said:

Okay, further testing done and I'm back to being puzzled. I don't have the DVI cable yet, but I've done some messing with the clock speeds and voltages of the card, specifically trying to underclock and undervolt.

At 500 core, 500 mem, -10% power, the lines are all but gone.
At 600 core, 500 mem, -10% power, the lines are back.
At 500/500 at standard power, the lines are faint but there.
At standard or overclocked speeds, at standard or higher voltage, the lines are worse.

Colour me confused. Here's hoping I don't need to RMA.

Click to expand...

Hey mate, I've got the same exact issue as you, with the same exact card.

The only solution I found was to use a DVI to DVI cable, VGA has too much interference and I don't know why because my DVI to VGA cable worked fine on my old card, my 5770. I don't full understand it myself, but the only solution has been to use a DVI cable so far.

Had this same issue a while ago only ever managed to sort it out completely by switching to a dvi to dvi connection. Things like vsync can make it a bit less visible.