[mythtv-users] new video card causing interference with cable signal

Rod Smith mythtv at rodsbooks.com
Sun Dec 6 15:34:17 UTC 2009

On Sunday 06 December 2009 02:12:59 am Greg Zornetzer wrote:
> Hi all,
> I recently got an MSI GT 220 512mb card to upgrade my myth box in
> perparation for 0.22.  While the new card does very well with decoding
> VDPAU, I've noticed a disturbing problem with several of my QAM HDTV signal
> quality - I see a lot of blockiness (as if the tuner is getting some kind
> of interference.  Removing the GT220 and going back to the motherboard's
> onboard graphics seems to cure the problem.  Does anyone have advice for
> some kind of makeshift shield to block interference from the graphics card?
> Or other ideas?
> My tuner card is a Pinnacle 800i (using the latest xc5000 driver) and I'm
> using 0.21-fixes for right now.

I've run into this sort of thing before, but even worse: On my main 
backend/frontend system, a pcHDTV 3000 is next to useless because of 
interference. I tried at least three different video cards in an effort to 
fix the problem. I did find significant differences, but the problem still 
existed with all the video cards I tried. I've never tried a physical shield, 
so I don't know if that would work. I did try moving the tuner to different 
PCI slots, to no avail. It's possible that swapping out the video card for 
another one would improve matters for you, so if nothing else you could try 
removing the video card in favor of another model. Even one from a different 
manufacturer but based on the same chipset might be an improvement. FWIW, I 
ended up replacing the pcHDTV 3000 with an AverTV A180. The A180 still has 
problems sometimes, but not nearly as bad as the pcHDTV. I eventually put the 
pcHDTV in another computer that functions as a slave backend, and it's 
flawless in there, so it's definitely not a defective card -- it's a 
defective interaction between the card and other components in the backend.

Rod Smith

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