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dead pixel policy for graphics cards

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Anonymous
a b U Graphics card
June 10, 2004 10:53:56 AM

Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

Here's a hypothetical question. If you were prepared to accept a
single dead pixel on an LCD display, would you also be prepared to
tolerate a single dead pixel in the video RAM of a graphics card? The
symptom would be the same.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
Anonymous
a b U Graphics card
June 10, 2004 10:53:57 AM

Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

> Here's a hypothetical question. If you were prepared to accept a
> single dead pixel on an LCD display, would you also be prepared to
> tolerate a single dead pixel in the video RAM of a graphics card? The
> symptom would be the same.

"pixels" rarely reside in a fixed address in videocard local memory, and I
understand yields for memory chips are much better than those of LCD panels
so there should be no excuse to not replace product with bad memory chip (or
fix the product otherwise).

Just recently bought dual channel ddr kit and the system was very unstable
so ran memory tester, and indeed the other module had errors on it. Got the
kit replaced no questions asked. With LCD's it could be a potential problem
to prove that the product is "defective" if there is a manufacturer policy
on dead pixels, the question is how many are willing to burn time and money
on court for a $400-$1500 LCD panel just on principle?

I wouldn't tolerate a single dead pixel on a LCD display either as a matter
of fact but that's another story.

I guess it would be wisest to get it written on the receipt that refund or
replacement is agreed on if there are any dead pixels. Advice I haven't
myself followed, but try to remember next time shopping for display.
Anonymous
a b U Graphics card
June 10, 2004 10:53:57 AM

Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

No such animal as a dead pixel due to a bad video card.

--
DaveW



"Franc Zabkar" <fzabkar@optussnet.com.au> wrote in message
news:7utec0lb1je9qct0afmqthgebere4thpv7@4ax.com...
> Here's a hypothetical question. If you were prepared to accept a
> single dead pixel on an LCD display, would you also be prepared to
> tolerate a single dead pixel in the video RAM of a graphics card? The
> symptom would be the same.
>
>
> - Franc Zabkar
> --
> Please remove one 's' from my address when replying by email.
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Anonymous
a b U Graphics card
June 11, 2004 10:14:43 AM

Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

On Wed, 09 Jun 2004 23:37:32 GMT, "DaveW" <none@zero.org> put finger
to keyboard and composed:

>No such animal as a dead pixel due to a bad video card.

I saw and repaired this *exact* problem on a monochrome VGU card in a
minicomputer CAD workstation some 15 years ago. This card had two 16KB
bitmaps consisting of 16 x 4116 DRAMs (16Kx1). The chips cost ~$1
each, so the major cost was my diagnostic time. BTW, the card cost
~$10K.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
Anonymous
a b U Graphics card
June 11, 2004 10:29:44 PM

Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

> >No such animal as a dead pixel due to a bad video card.
>
> I saw and repaired this *exact* problem on a monochrome VGU card in a
> minicomputer CAD workstation some 15 years ago. This card had two 16KB
> bitmaps consisting of 16 x 4116 DRAMs (16Kx1). The chips cost ~$1
> each, so the major cost was my diagnostic time. BTW, the card cost
> ~$10K.

I figed my Gravis Ultrasound 512 (+512) using the same methods, back then
the memory wasn't soldered and much less hassle to switch. I salvaged the
memory from old VGA card, actually but that is besides the point.

Memory is not in fixed address in modern OS and hardware compo, because the
memory is allocated for surfaces as it is needed by the memory controller in
the card. So the address of memory that is defective could end up storing
practically anything. If it happens to store indexbuffer, and using index
out-of-range to cause the graphics processor or it's memory controller to
read or write on top of something else it relies on, such as vertex- or
fragment program (or anything I cannot think of off-the-hip) causing the
hardware to go into endless loop or otherwise crash, freeze, anything.

Such product would be unstable and untrustworthy, that is the bottom line.
Dead pixel on LCD display is more likely to be only a cosmetic defect.
Defective memory on the other hand opens a completely new can of worms. I
just had unstable system because of defective DDR dual channel memory kit,
it was wonder if the system stayed up 15 minutes at a time. GPU != CPU+MB
but it's hardly comparable to a "dead pixel" on LCD either.

Memory manufacturers don't have the luxury of not having a full warranty for
their products: the yields are too good for that with the cost of producing
a wafer. Can someone quote typical % of waste for TFT/LCD displays assuming
1280x1024 and zero dead pixel tolerance? Any manufacturer will do for
starters, I'm too handicapped and stupid to find such information myself
(okay, didn't even try to look.. if anyone has information at his fingertips
please share, thanks!). Obviously there is TOO MUCH waste for some
manufacturers liking if they have policy of X dead pixels, say, 3-5 per
display. If they had zero tolerance I bet the prices would have to be
higher, and if they keep prices too high I would assume their displays
wouldn't be so "competitive" .. I think a "defect" in their products most
consumers don't even know is there is better than obvious price defect that
would be the alternative (price defect == higher, thus non-competitive
retail price).

IMHO, I think this situation is direct result of price competition. People
are willing to pay for Good Enough as long as it is also Cheap Enough. I
could be wrong.
Or am I just stupid to come to such conclusions?
Anonymous
a b U Graphics card
June 11, 2004 10:31:43 PM

Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

On Thu, 10 Jun 2004 01:06:31 +0300, "joe smith"
<rapu@ra73727uashduashfh.org> put finger to keyboard and composed:

>I wouldn't tolerate a single dead pixel on a LCD display either as a matter
>of fact but that's another story.

The purpose of my post was to gauge people's tolerance for defects,
and to find out whether they would differentiate between two distinct
faults which produced the same effect. IMO, for a user to say that a
dead pixel produced by a faulty display is less annoying than the same
dead pixel in video RAM is somewhat of a double standard.

>I guess it would be wisest to get it written on the receipt that refund or
>replacement is agreed on if there are any dead pixels.

I would think that the onus should be on the manufacturer to make the
customer aware of any defect policy at the time of purchase. In the
absence of any such disclaimer, the customer has every right to expect
that the product will be defect free right out of the box, and that
any new defects will be made good during the warranty period.

> Advice I haven't
>myself followed, but try to remember next time shopping for display.

FWIW, I've been using a defect free Mitsubishi Diamond View DV152 15"
LCD monitor for nearly three years now. At the time of purchase there
was no mention of a dead pixel policy in the user manual, or the
warranty card, nor did the vendor advise me of same. It's only
recently that I discovered a "Pixel Defect Specification" for my
particular monitor on Mitsubishi's Australian website.

http://www.mitsubishi-electric.com.au/files/tft/pixel_s...


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
Anonymous
a b U Graphics card
June 12, 2004 10:22:02 PM

Archived from groups: comp.sys.ibm.pc.hardware.video (More info?)

On Fri, 11 Jun 2004 18:29:44 +0300, "joe smith"
<rapu@ra73727uashduashfh.org> put finger to keyboard and composed:

>> >No such animal as a dead pixel due to a bad video card.
>>
>> I saw and repaired this *exact* problem on a monochrome VGU card in a
>> minicomputer CAD workstation some 15 years ago. This card had two 16KB
>> bitmaps consisting of 16 x 4116 DRAMs (16Kx1). The chips cost ~$1
>> each, so the major cost was my diagnostic time. BTW, the card cost
>> ~$10K.
>
>I figed my Gravis Ultrasound 512 (+512) using the same methods, back then
>the memory wasn't soldered and much less hassle to switch. I salvaged the
>memory from old VGA card, actually but that is besides the point.
>
>Memory is not in fixed address in modern OS and hardware compo, because the
>memory is allocated for surfaces as it is needed by the memory controller in
>the card. So the address of memory that is defective could end up storing
>practically anything. If it happens to store indexbuffer, and using index
>out-of-range to cause the graphics processor or it's memory controller to
>read or write on top of something else it relies on, such as vertex- or
>fragment program (or anything I cannot think of off-the-hip) causing the
>hardware to go into endless loop or otherwise crash, freeze, anything.

I see your point. Incidentally, the CAD system I referred to above had
a separate GPU board, which in turn had separate memory boards. A
colour W/S had three VGU cards, one each for RGB. I guess we've come a
long way since then.


- Franc Zabkar
--
Please remove one 's' from my address when replying by email.
!