DVI/wifi interference

I have a WMP54G ver. 1 pci card, and an ASUS 9600 radeon w/ DVI output.

When I plug in my monitor (viewsonic VP930B) to the DVI port my wireless
connection gets disturbed. At 75Hz refresh rate my connection is barely
useable - lots of dropped packets and ping times to my wrt54g router are
very long (>1s). Dropping the refresh rate to 70Hz improves things a lot (1
to 30ms ping times, only a few dropped packets) but the connection's still
not quite right. Disconnecting the DVI entirely and using the D-sub port,
the connection is perfect.

I've tried replacing the cable with the one my friend uses with 75Hz and the
same wireless card, and the problem's still there (so perhaps it's a
software issue and not RFI?)

Google's been no help for this one...Anyone encountered this before? Have
any suggestions?

Thanks,

Dave




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"David Grant" <(E-Mail Removed)> wrote in message
news:44fdc156$0$19731$(E-Mail Removed).. .
> I have a WMP54G ver. 1 pci card, and an ASUS 9600 radeon w/ DVI output.
>
> When I plug in my monitor (viewsonic VP930B) to the DVI port my wireless
> connection gets disturbed. At 75Hz refresh rate my connection is barely
> useable - lots of dropped packets and ping times to my wrt54g router are
> very long (>1s). Dropping the refresh rate to 70Hz improves things a lot
(1
> to 30ms ping times, only a few dropped packets) but the connection's still
> not quite right. Disconnecting the DVI entirely and using the D-sub port,
> the connection is perfect.
>
> I've tried replacing the cable with the one my friend uses with 75Hz and
the
> same wireless card, and the problem's still there (so perhaps it's a
> software issue and not RFI?)

Are there any ferrite blocks on the cable? You could try adding some.

Does it make a difference if the monitor is on/off? That might tell you if
it's the cable or the monitor that's leaking.

Does the wireless card have an antenna that can be relocated? Some have an
antenna you can remove and replace with one on a cable.

Is the mounting screw on the graphics card fitted (the one that holds the
panel into the PC)?

"CWatters" <(E-Mail Removed)> wrote in message
news:44fdd203$0$3595$(E-Mail Removed)...
>
> "David Grant" <(E-Mail Removed)> wrote in message
> news:44fdc156$0$19731$(E-Mail Removed).. .
>> I have a WMP54G ver. 1 pci card, and an ASUS 9600 radeon w/ DVI output.
>>
>> When I plug in my monitor (viewsonic VP930B) to the DVI port my wireless
>> connection gets disturbed. At 75Hz refresh rate my connection is barely
>> useable - lots of dropped packets and ping times to my wrt54g router are
>> very long (>1s). Dropping the refresh rate to 70Hz improves things a lot
> (1
>> to 30ms ping times, only a few dropped packets) but the connection's
>> still
>> not quite right. Disconnecting the DVI entirely and using the D-sub port,
>> the connection is perfect.
>>
>> I've tried replacing the cable with the one my friend uses with 75Hz and
> the
>> same wireless card, and the problem's still there (so perhaps it's a
>> software issue and not RFI?)
>
> Are there any ferrite blocks on the cable? You could try adding some.
>
> Does it make a difference if the monitor is on/off? That might tell you if
> it's the cable or the monitor that's leaking.

No, see below

>
> Does the wireless card have an antenna that can be relocated? Some have an
> antenna you can remove and replace with one on a cable.

Maybe, it's the stock WMP54G antenna - but see below.

>
> Is the mounting screw on the graphics card fitted (the one that holds the
> panel into the PC)?

Yes.

I played around a bit more today and noticed that the ping/packet-loss rate
changes with the 2nd (VGA port) monitor refresh rate. For a few minutes I
can run the DVI monitor at 75Hz if I lower the VGA monitor to 72 or 70Hz -
but the ping time increases exponentially after a couple minutes and then
the connection dies until I change the refresh rate (doesn't matter what I
change it to, it works for a few minutes regardless of the rate). This
doesn't seem like RFI to me, more like a driver problem or some other
internal conflict. Anyone beg to differ? I'm gonna try moving the linksys
pci card to a different slot and see if that changes anything.



--
Posted via a free Usenet account from http://www.teranews.com

> I played around a bit more today and noticed that the ping/packet-loss
rate
> changes with the 2nd (VGA port) monitor refresh rate. For a few minutes I
> can run the DVI monitor at 75Hz if I lower the VGA monitor to 72 or 70Hz -
> but the ping time increases exponentially after a couple minutes and then
> the connection dies until I change the refresh rate (doesn't matter what I
> change it to, it works for a few minutes regardless of the rate). This
> doesn't seem like RFI to me, more like a driver problem or some other
> internal conflict. Anyone beg to differ? I'm gonna try moving the linksys
> pci card to a different slot and see if that changes anything.

If it's not RFI then make sure the two cards are not sharing an IRQ
(interrupt). Some PCs have a PCI buss that shares interrupts between
certain slots. This can be a real pain in the ass to debug if you've got
anything more than just one or two cards.

"Bill Kearney" <(E-Mail Removed)> wrote in message
news:NN-(E-Mail Removed)...
>> I played around a bit more today and noticed that the ping/packet-loss
> rate
>> changes with the 2nd (VGA port) monitor refresh rate. For a few minutes I
>> can run the DVI monitor at 75Hz if I lower the VGA monitor to 72 or
>> 70Hz -
>> but the ping time increases exponentially after a couple minutes and then
>> the connection dies until I change the refresh rate (doesn't matter what
>> I
>> change it to, it works for a few minutes regardless of the rate). This
>> doesn't seem like RFI to me, more like a driver problem or some other
>> internal conflict. Anyone beg to differ? I'm gonna try moving the linksys
>> pci card to a different slot and see if that changes anything.
>
> If it's not RFI then make sure the two cards are not sharing an IRQ
> (interrupt). Some PCs have a PCI buss that shares interrupts between
> certain slots. This can be a real pain in the ass to debug if you've got
> anything more than just one or two cards.
>

Tried all pci slots and no luck (linksys is the only pci card and radeon is
agp). Gonna try another linksys card at some point.

Another thing i noticed is that when the CPU is occupied (when loading a
program like outlook) ping times jump up over 1 sec. Is this normal for a
modern-day PC (2.8ghz intel) or is this a sign I have some sort of bus
issue?



--
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I too have been having interference problems with my viewsonic VP930B
but not with a wireless network connection but with a wireless
keyboard.

I have tried 3 different wireless keyboards in close proximity to the
screen all exhibiting similar effects: Dropped keystrokes & reduced
battery life.

At first i thought it was the keyboards, then the computer. Only today
did it dawn on me that it might be the screen. The dvi & vga cables
that come with the screen have built in ferrite blocks. What is cuasing
this is probably improper sheilding on the power supply.

David Grant wrote:
> "Bill Kearney" <(E-Mail Removed)> wrote in message
> news:NN-(E-Mail Removed)...
> >> I played around a bit more today and noticed that the ping/packet-loss
> > rate
> >> changes with the 2nd (VGA port) monitor refresh rate. For a few minutes I
> >> can run the DVI monitor at 75Hz if I lower the VGA monitor to 72 or
> >> 70Hz -
> >> but the ping time increases exponentially after a couple minutes and then
> >> the connection dies until I change the refresh rate (doesn't matter what
> >> I
> >> change it to, it works for a few minutes regardless of the rate). This
> >> doesn't seem like RFI to me, more like a driver problem or some other
> >> internal conflict. Anyone beg to differ? I'm gonna try moving the linksys
> >> pci card to a different slot and see if that changes anything.
> >
> > If it's not RFI then make sure the two cards are not sharing an IRQ
> > (interrupt). Some PCs have a PCI buss that shares interrupts between
> > certain slots. This can be a real pain in the ass to debug if you've got
> > anything more than just one or two cards.
> >
>
> Tried all pci slots and no luck (linksys is the only pci card and radeon is
> agp). Gonna try another linksys card at some point.
>
> Another thing i noticed is that when the CPU is occupied (when loading a
> program like outlook) ping times jump up over 1 sec. Is this normal for a
> modern-day PC (2.8ghz intel) or is this a sign I have some sort of bus
> issue?
>
>
>
> --
> Posted via a free Usenet account from http://www.teranews.com

"BlindWanderer" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed) oups.com...
> I too have been having interference problems with my viewsonic VP930B
> but not with a wireless network connection but with a wireless
> keyboard.
>
> I have tried 3 different wireless keyboards in close proximity to the
> screen all exhibiting similar effects: Dropped keystrokes & reduced
> battery life.
>
> At first i thought it was the keyboards, then the computer. Only today
> did it dawn on me that it might be the screen. The dvi & vga cables
> that come with the screen have built in ferrite blocks. What is cuasing
> this is probably improper sheilding on the power supply.

yes it might be worth trying a ferrite block (ex: from Maplin) on the
monitor power lead - near the monitor - but it could be leaking out of
anywhere. Are you using the power lead supplied with it?

In a past life I've spent time in a lab down a salt mine trying to solve RFI
problems. Somtimes it was a bitch to locate the cause and find a fix. We
used special recievers and spectrum analysers to identify offending
frequencies/harmonics. That sometimes allowed you to work out what part of
the system it was coming from. Sometimes wrapping offending equipment in
aluminium foil helped reveal where the problem was.

Someone once spent several days trying to find out why a computer was
apparently radaiting only to trace the fault to the power supply of some new
test equipment we were using! It wasn't coming from the computer at all. He
called up the manufacturer and they admitted that they hadn't been able to
get their kit to meet the CE standard but had put the sticker on anyway.