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- Newsgroups: comp.sys.mac.hardware
- Path: sparky!uunet!cs.utexas.edu!zaphod.mps.ohio-state.edu!rpi!psinntp!psinntp!newstand.syr.edu!rodan.acs.syr.edu!isr
- From: isr@rodan.acs.syr.edu (Michael S. Schechter - ISR group account)
- Subject: Re: Re: Lifetime of 25MHz IIsi (was: 25MHz IIsi and my engineering friend)
- Message-ID: <1992Nov20.114502.27711@newstand.syr.edu>
- Organization: Syracuse University, Syracuse, NY
- References: <1992Nov16.181708.22881@news.uni-stuttgart.de> <71610003@hpl-opus.hpl.hp.com>
- Date: Fri, 20 Nov 92 11:45:02 EST
- Lines: 54
-
- In article <71610003@hpl-opus.hpl.hp.com> blalock@hpl-opus.hpl.hp.com (Travis Blalock) writes:
- >In comp.sys.mac.hardware, blalock@hpl-otis.hpl.hp.com (Travis Blalock) writes:
- >> In comp.sys.mac.hardware, isr@rodan.acs.syr.edu (Michael S. Schechter - ISR group account) writes:
- >> > they'll be more voltrage drop, and the CPU will draw still more amperage,
- >> Ack! Less voltage --> lower current
- >Clarification: Some folks don't understand why I am referring to this
- >situation as less voltage. The power supply voltage is fixed. More voltage
- >drop on the PC board trace between the supply and the CPU chip means there is
- >less voltage across the CPU chip. If the CPU has less voltage across
- >it, it will draw less current.
-
- Oh well, as the original "heat" poster, I see my point needs
- more clarification.. Travis, you clearly understand device charecteristics
- but there's still the BIG picture that you and several others haven't
- "gotten" yet.
-
- I was referring to the traces sucking up more power..
- as their temperature goes up, their resistance goes up, and their fraction
- of voltage goes up meaning more voltage drop across them, meaning
- more power consumed, meaning more heat, and more resistance, then
- it starts over again...
-
- eventually they'll be little pockets of copper vapor exploding outwads
- from the inner layers, sending shards of boards all over the inside of
- computer. And when THAT happens, well, I don't think it'll be very
- good for the power supply if say, a peice of motherboard lands across
- two relatively hot pins/traces..
-
- And as far as the chip goes, well, if the section of board that explodes
- happens to lie in the vicinity of the 030, what kind of mechanical stress
- will that put on the ceramic? Yes, that chip may very well be shock-rated
- to 200G's, but is it bend-rated? how fault-tolerant is it, anyway?
- is there a ratng for how many internalcracks it may develop before
- failure?
-
- So, the BIG picture is...
- Some people are worried about EVERYTHING. tell 'em that heat sinks
- keep things from getting HOT, and they worry abouyt long-term effects,
- tell 'em about that they worry about something else. it's always something.
-
- So, ya might as well tell 'em that their si'll explode in their face,
- since none of 'em will ever do anything BUT worry. Since now they've
-
- go ahead y'all, flame me now, while ya gots the chance.
-
- flames to: Mike_Schecter@isr.syr.edu
- really hot flames to: isr@mailbox.syr.edu (So we can pass it around)
- complaints to: postmaster@isr.syr.edu (oh-oh!)
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