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- Newsgroups: comp.sys.mac.system
- Path: sparky!uunet!wupost!zaphod.mps.ohio-state.edu!caen!batcomputer!lynx.msc.cornell.edu!esther.msc.cornell.edu!maynard
- From: maynard@esther.msc.cornell.edu (Maynard J. Handley)
- Subject: Re: 25MHz vs. 16MHz
- Message-ID: <1992Jul22.130117.15078@msc.cornell.edu>
- Sender: news@msc.cornell.edu
- Organization: Cornell-Materials-Science-Center
- References: <1992Jul15.223600.16914@sagpd1> <1992Jul19.011310.24290@smsc.sony.com> <4ePFb=m00WBKQ0o_0L@andrew.cmu.edu>
- Date: Wed, 22 Jul 1992 13:01:17 GMT
- Lines: 23
-
- >Apple is very cautios i've found out. Apple supposably got only 33MHz
- >040s for its Quadra Line. Only clocking the 700 and 900 at 25MHz for a
- >couple of possible reasons:
- >1. They wanted to 'play it safe'
- >2. 25MHz [outside] already made it 4times faster than a ci, why go all
- >the way at once?
- >3. Price discrimination
- >
- >I don't know why they did it [A company is making OverDrive to clock em
- >at 33], but it just goes back to Apple's insistence on high quality
- >
- >As for PCs, I've heard that Compaq is the best ibox and IBM is pretty
- >good too. But i wouldn't trade my 700 for any PC :-)
-
- It was my understanding that often chips fail at higher speeds because they
- become too hot. The implication is that if they are cooled externally they
- can often be driven safely at higher speeds, so it can be legit to run them
- in overdrive. The problem is that the cooling is sometimes not trivial. It
- is possible to introduce steep temperature gradients in the chip that cause
- it to die sooner (I guess you're promoting the migration of the dopants, or
- maybe its just mechanical stress from expansion/contraction.)
-
- Maynard Handley
-