Archived from groups: comp.sys.ibm.pc.hardware.chips (
More info?)
On Thu, 30 Dec 2004 23:46:52 +0200, "cquirke (MVP Win9x)"
<cquirkenews@nospam.mvps.org> wrote:
>On Wed, 29 Dec 2004 07:37:25 -0500, George Macdonald
>>On Tue, 28 Dec 2004 13:07:58 +0200, "cquirke (MVP Win9x)"
>
>>>Ah: This is the perfect place to muse about bad caps
>>>I'm not sure if heat is a required factor in capacitor breakdown.
>
>>Yes the original IEEE story was here:
>>http://www.spectrum.ieee.org/WEBONLY/resource/feb03/ncap.html
>
>That's the one I read, too.
>
>>more at
http://www.niccomp.com/taiwanlowesr.htm where it's mentioned that
>>it was a double defection and theft -
>
>Nice links from there...
>
>http://www.low-esr.com/
>
>...seem to confirm what I see as a common failure pattern in 815G and
>845G (when built-in SVGA used); ripple interference effects on screen,
>which prompts a look inside that shows bulging or leaking caps.
>
>>From an industry-naive chemistry viewpoint, water based electrolytes *do*
>>seem like a bad idea with the current temps around a CPU & its VR on a
>>modern mbrd. I think the OP was suggesting that this 2nd round of failures
>>was related more to the increasing temps the capacitors were subjected to
>
>Temp is a factor, yeah, though the graphs seem happy at typical case
>temps (45C is common with Prescott).
I got the hint that it was (extra) heat+age causing drying out of the
electrolyte more quickly.
>I followed a few links off Low-ESR.com and they make interesting
>reading. For example, they mention liquid-centered caps use ionic
>rather than electronic conduction which is slower; that implies a need
>to have the electrolysis effect, and thus a polar liquid.
Hmmm, and water is err, free.
... well purify and dope it for the
purpose.
>>Could be that the electrolytic's days are numbered
>
>The problem is getting the capacitance required. So far, combination
>liquid plus solid can't get up there, though they extend the range of
>the smaller purely solid capacitors.
>
>>I've no idea what the ramifications might be for mbrd circuitry if
>>designers are forced to go to solids.
>
>Well, they already talk about capacitor *banks* (of electrolytics) so
>to get the same capacity in solic caps is going to be ugly. They also
>note that liquid caps fail open-circuit, whereas solids can combust;
>that may be a safety factor, too.
>
>>>What's interesting is that no-one has been able to maintain a list of
>>>affected motherboard brands, for fear of litigation etc.
>
>>The two prime culprits/victims would appear to be Abit and MSI - at least
>>their names seem to be mentioned frequently in the anecdotal reports in the
>>forums at places like www.badcaps.net
>
>The ones I see here have been DFI, JetWay and Gigabyte - i.e. all of
>the motherboards commonly used or seen from that time.
I wish there was a clearer picture of how much the defective electrolyte
was to blame globally and to what extent we're talking about low-cost
capacitor mfrs who don't have any capacitor technology but turn out cheap
junk... and to what extent the "expert" mfrs are just hitting the wall on
current technology. There's just an apparent mix of things which went
wrong, which gives an impression of pot-luck to us.
>I've started using Intel motherboards (as opposed to motherboards
>based on Intel chipsets) in the 865G era, but it's too early to tell
>whether this will avoid the problem. So Far, So Good.
I've been led to believe that Intel desktop mbrds are coming from
same/similar PCB factories as everybody else... but if you get consistent
quality that's what really matters. I have some MSI K7 mbrds coming up for
2 years - I guess I'd better check them for capacitors with swollen
tops.
Rgds, George Macdonald
"Just because they're paranoid doesn't mean you're not psychotic" - Who, me??
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