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Date Posted: 05:05:49 08/07/01 Tue
Author: Chris Lawson
Subject: Re: PowerCard 100 on a clock chipped LC575 logic board?
In reply to: Jeffrey G 's message, "PowerCard 100 on a clock chipped LC575 logic board?" on 20:05:49 08/06/01 Mon

What Stuart says is pretty good advice. As a guy who runs a lot of his Macs a lot faster than they ought to be running, allow me to add to that :)

Running an 040 at anywhere from 25-50% overclocking seems to work just about flawlessly in most cases. The exception I've found is the Radius Rocket, which was overheating at 50.000 MHz (o/c from 40.000 MHz) and technically isn't a Mac anyway :)

The 601 is a good deal harder to cool effectively, especially in a case like a CC's with such tight space and airflow restrictions. While I'm not familiar with the 100MHz PowerCard heatsink, I know the one on the Turbo 601 (and Apple 040 PDS-slot PPC upgrades like that for the Q9x0, Q700, etc.) is a pretty large affair that doesn't take easily to either a Peltier device or a fan.

If there's any way you think you can do it, putting a small Peltier (ideally the same size as the contact area between the chip and heatsink to prevent condensation*) on the CPU and a fan on the heatsink to cool that is probably your best bet. Might wanna start off with just a fan since that might be sufficient, and if it is, there's no need to spend another $15-20 on a Peltier, which will pull 12V current like you wouldn't believe. There are a buncha places online that sell fans that piggyback off the HD power connector. Just measure the inside dimensions of the heatsink (if it's like the Turbo 601 heatsink) and use that to figure out what size fan you need.

If, as the case may be, the heatsink is a finned heatsink more like those found on the full 040s in Macs that shipped with one (or like the new G3/G4 heatsinks), your options might be somewhat better. If you're lucky, you can find a heatsink-fan combination online of the same dimensions as the stock heatsink. The fan should be able to piggyback off the HD power connector.

If the bottom of the heatsink is flat and makes contact over much of its surface area (the 601 heatsinks I've seen only contacted the CPU in a small square at the centre of the heatsink), you can probably use a Peltier quite easily.

There's always an option like this if you're really serious about it :)

*Peltiers WILL produce frost or dew (depending on various factors such as temperature differential across the Peltier, ambient temperature, etc.) on their "cool" side if left in contact with air. Water and electronics don't tend to get along really well, so you would be advised to cover any exposed areas on the "cool" side with a layer of heatsink grease so as to avoid condensation on or near the CPU.

BTW: using a 21MHz oscillator will give a PowerCard speed of 126MHz, not 125 :) Might wanna step back to a 20 or 20.5 if you can't get the 21 to be stable. Digi-Key has lots and lots and LOTS of crystals, and Fox can custom-build an oscillator in the frequency you want in about two weeks for under $15.

cl

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Replies:

Re: PowerCard 100 on a clock chipped LC575 logic board? -- Jeffrey G, 16:41:45 08/07/01 Tue
- Re: PowerCard 100 on a clock chipped LC575 logic board? -- Chris Lawson, 18:07:24 08/07/01 Tue
  - Re: PowerCard 100 on a clock chipped LC575 logic board? -- Dr. Webster, 20:07:00 08/07/01 Tue
  - Re: PowerCard 100 on a clock chipped LC575 logic board? -- Bruce (in Orlando), 12:00:36 08/08/01 Wed
    - Re: PowerCard 100 on a clock chipped LC575 logic board? -- Chris Lawson, 13:09:58 08/08/01 Wed
    - Re: PowerCard 100 on a clock chipped LC575 logic board? -- Chris Lawson, 13:23:44 08/08/01 Wed
    - Re: PowerCard 100 on a clock chipped LC575 logic board? -- Jeffrey G, 00:27:00 08/09/01 Thu
      - Clocked CC/575s -- Stuart Bell, 00:36:03 08/09/01 Thu
        Re: Clocked CC/575s -- Chris Lawson, 04:53:42 08/09/01 Thu
        Re: Clocked CC/575s -- Jeffrey G, 05:40:32 08/09/01 Thu