[cdhostage]

I've been seroiusly upgrading my Powerbook recently, getting PowerLogix to swap in a 900 MHz G3 and maxing out the RAM. There's a new HD in the mail.

The original setup had what I thought was a heatpipe leading over to a crenulated heatsink. The fan was set up so that iif the processor got too hot, the fan would blow air from an underside vent up against the heatsink, around it, and exit immediately above the fan. With a 400 MHz G3, the fan almost never went on.

The PowerLogix upgrade discarded the heatpipe setup in favor of a 3 inch square thin plate of copper and some thermal paste connected directly to the shield overhead. This is not the best solution, as that shield is an EMI shield for the processor, and now probably trasmits all sorts of electrical intereference to it. The heatsink setup wouldn't fit inside the case anymore, so I broke it over a trah can to see what it was made of, expecting to see a few drops of liquid coming out of the heatpipe. No! It's just a mass of thin copper wires encased in aluminum leading to the aluminum heatsink by the ventilation slots. I guess I was misinformed.

Come to think of it, standard thermal paste is not electrically conductive, so the processor is isolated from static and induction.

The current setup works fine for ordinary use (the G3 spends much of its time throttled to 550 MHz), but I want to be able to run Folding@Home again without the constant loud fan.

I don't use the internal modem, so that frees up some space inside. I can probably fit a real heatpipe setup and a different fan in the space that the current fan and modem take.

There are a whole lot of mod sites out there, and they're all very informative for desktop machines. Most of the heating solutions are simply too large, and it seems that most notebook fan setups blow out the bottom. Where can I find a small fan?

[bmhome1]

Using the heat shield as a large heat sink (the copper piece gets thermal paste on top too to conduct heat upwards, correct?) seems like a poor solution for heat dissipation with the 900 upgrade.

Doesn't the RAM under the heat shield and the keyboard area above that get really hot now? Seems like the original heat pipe (now that we know it isn't liquid-filled) could be milled down thinner where the pipe contacts the chip. The heat pipe is only 1/8" thick and the copper piece (50 mil I believe) is only about half that thick, so it seems the difference to achieve is rather small actually. At least without one in hand to examine.

I don't have a 900 yet, but am planning on trying out the above idea when I get one. I've managed to stock up on a couple extra Pismo heat pipes for the experiment.

Is the 900 chip all that much taller mounted on the processor card? Is there an adaptor socket too, or is it flat just like the original G3?

Also, did you try Artic Silver heat sink compound? I see claims that using it can drop temps a few extra degrees compared to generic pastes (its 99% silver powder).

[cdhostage]

It's interesting - the new proc stands no higher than the old one, as far as I can tell. I didn't do any measurements beforehand, so I'm not sure. The current situation conducts heat upward into the copper plate into the heat shield, each connected by some generic thermal paste. The heat shield is connected on all edges to the steel (aluminum?) stiffener frame, and contacts the keyboard directly, although the keyboard is not very conductive, so it never gets uncomfortable to type. Or try typing, anyway, because I've been having keyboard problems.

I think that the copper block is there mostly as a heat spreader, quickly conducting heat away from the proc and spreading it to the shield and thence the frame. It's also helpful that it's a good weighty piece of metal (perhaps 2 oz which is... 50 grams?) and can absorb extra heat during hot moments, and conduct it away faster than slow moments supply it.

Heat pipes, as far as I can understand, are effective at a particular range of temperatures - the ones that came with the Pismo were meant to siphon heat away from the low-power 400 MHz G3 chip. If the pipe gets too hot, the gas boiled at one end can't condense at the other end.
I think I know what I saw now in my broken heat pipe - the "wires" I saw were the capillary tubes ringing the inside surface, and the working fluid evaporated as soon as I exposed it to ordinary pressure. I can't know for sure, though.

[bmhome1]

My post above should have read 50 gauge (not 50 mil) which is about 1/16" thick. If that's correct, then the heat pipe is only about 1/16" too thick.

FastMac's G4 550mz processor upgrade for the Pismo does reuse the original heat pipe, so the temperature ranges the heat pipe effectively conducts should work for the G3 900mz also, which I believe is one of the new-generation low-power series.

Does the G3 900 report chip core temps with OSX Temperature Monitor or ThermoInDock (even though the accuracy is low)?

[Powerbook]

cdhostage: All in all - are you dissatisfied with the upgrade result? When running 900MHz is the fan always on? (e.g. with 3D games). The 550 Mhz throttling has been choosen by you - and are other steps possible?
Pics of processor & heatsink please?

bmhome1: Thanks for posting - I didn't even know of FastMac. I will mail them to ask for a G3 Update!!!

Regards,
Powerbook

[cdhostage]

Originally posted by Powerbook:
cdhostage: All in all - are you dissatisfied with the upgrade result? When running 900MHz is the fan always on? (e.g. with 3D games). The 550 Mhz throttling has been choosen by you - and are other steps possible?
Pics of processor & heatsink please?

Nah, it's quite Snappy! The fan doesn't turn on when the computer is idle, nor during Internetting or word processing. When the CPU is maxed out doing Folding@Home or DVD-playing, however, it takes about three minutes for the fan to turn on. The Pismo hasn't crashed in a while since I reapplied thermal paste, but my main concern is that this friggin loud fan goes on and might not be doing anything.

I didn't choose 550 MHz - that's just what the Apple System Profiler reports, and the "About This Mac" up in the Apple Menu, too. I know that the Pismo rips MP3s at more than twice the rate it used to, and that the Finder is quick. I am not nearly competent enough to tinker with the thing.

I think that PowerLogix didn't connect up the thermocouple - all the temp programs on Versiontracker read -1 degrees Celcius or report nothing.

[Spliffdaddy]

Just because you didn't see any liquid in the heatpipe doesn't mean it didn't contain some sort of fluid. The copper wires were likely the 'wicking agents' for a fluid that evaporated upon exposure to air.

Copper wires would be entirely non-effective at transferring heat over any distance more than a cm or 2. While copper is a good heat conductor, it's still 1000 times worse than a heatpipe.


I agree the cooling solution provided with the CPU upgrade is iffy at best, and potentially disastrous at worst.

[zeekyhbomb44875]

could you somehow have a copper heat sink milled, with a copper sheet as thick as you can fit, going over to a finned heatsink mass in where the modem (was) and mount a small fan in the end spot, where the phone line plugs into. you could use a 12V 40mm fan and run it at the 5 volts, or maybe the boltage the battery runs at (i dont know what V this is tho :-| if the 5 volts is too loud for your taste, you could use a resistor in series with the fan to lower it's voltage a tad. if this doesnt keep the CPU cool enough, you could somehow get a fan giving airflow under the keyboard, directly across those plates. you would have to do some hard core mods to the powerbook, tho to keep the KB raised a tad. you'd have to lift the display's hinges up some (maybe 5-7 mm? and then extend the latch on the front side of the book. then fab mounts to keep the KB raised, then devise a plan for the fan scheme, along the heatsink. and if room permitted it, you could use a real finned copper heatsink instead of the metal plate they call a heat sink. im givin myself some ideas here :-)

BTW, i'm modding my wallstreet a BIT, removing the rubbery stuff from the aluminum plates on top and bottom of the lappy, and im going to paint it. i have vut out the apple on the top of the computer, into a circle, and i will either make a plexiglass or lexan circle to fill in the area, backed with white, and sporting a picture of tux (the linux penguin) as i will be running mandrake on it. i also plan to overclock it, and add whatever cooling necessary. i'm considering hacking a capacitor onto the PLL to raise the bus speed of the CPU and overall system, i'll see how everything goes till that point tho. if you want help on the topic of cooling, im sure that the kind folks at the overclockers.com forums (http://forums.oc-forums.com/vb/index.php) in the cooling forums will be glad to help you find some ideas, and in the services forum (classifieds, services) under custom water blocks im sure that he could mill up a small HS to your specs. (BTW, i am four4875 at the OC forums )

i hope i have helped someone with this rambling, and i further hope it made sence.