Pismo G4 550Mhz Upgrade, overheating issues

[GorfTheChosen]

As the thread title suggests I have serious overheating issues when the processor is under prolonged heavy loads.

This occurs when the computer is working on processor-intensive tasks of long(er) duration (>30 minutes)

The issue appears to be entirely due to the fact that computer's fan will not come on before the computer overheats and locks up. In fact it doesn't come ... ever. I know it used to ... back in the day ...

I have unbuttoned the keyboard and flipped it out of the way then placed a small 5v fan directly over the processor heatsink (powered by a USB cable from another computer) and have not been able to get it to overheat and lock up after running it hard continuously for over 2 hours:



Have tried resetting the NVRAM.

Have NOT resent the Power Manager yet though.

I have tried getting it to run an OF script at boot which supposedly resets the settings for the stock fan to lower the on/off temperature values. Still doesn't come on ... but getting the script to actually run may be problematic (due to multiple partitions on the drive as I understand it)

Installed a modified "AppleThermal.kext" - that was specifically done for the Pismo - that purports to lower the on/off temperature settings for the fan.

After addressing some issues with that "installation" still got no activity from the stock fan.

May still have issues with the "installation" of that kext though ?

I suspected that maybe the fan was bad.

So I pulled the fan plug out of the header on the logic board and used the above mentioned USB cable to feed it 5v ... fan spins up and runs fine.

So then I wondered whether might be a dicey connection from the logic board to the header ... hard to tell visually for sure (connections/pads are tiny and my eyesight isn't all that great ... even with the assistance of lots of light and magnification) so I plugged the fan harness back into the header and fed 5v to the solder dimples on the two pads that the header is connected to. Fan spins up and runs fine.

Right now I have the machine torn apart to address some reassembly issues that I missed on the first go-round.

I would be happy to hard wire the stock fan to a 5v source so that it is always on whenever the Pismo is on ... but I lack the necessary knowledge/expertise to go poking around on the internal components trying to find a power source and apparently there no schematics available.

Pulling power from anything drive or battery-related seems to me to be kind of dicey ... for obvious and maybe not so obvious reasons.

Last night I pulled the modem because at this point, given the ubiquity of wifi, it's pretty much dead weight.

I was hoping to shoehorn a small blower fan under the processor heatsink. It looks like that can be done ... after removal of one small plastic tab on the bottom case that apparently served no discernible purpose:



Another possibility is the hdd drive bay (now occupied by the Ablecon adapter and mSATA SSD) where the air intake vent is:



... although the clearances issues there may be too much to overcome.

In any event, a power source still remains an issue.

To that end, after thinking about it a bit, I thought that the easiest and least likely to cause problems way to tap a power source was the incoming power from the AC power adapter. That seemed like a good possibility ... since the times when the computer is going to be working this hard it will be plugged into external power.

The issue is the incoming power is 24v and the fans are 5v.

To solve that issue I was considering using a small Buck Converter board like the one linked below, soldered to the incoming power feed which can be seen in the above photo:

MP1584EN 5pcs Mini 5V Buck Converter Board - 5-30V to 5V, 1.8A Output, Small Size, Black

That thing is tiny ... so it might be possible to shoehorn in there. And the power draw is minimal.

Honestly, the most preferable route would be to get the stock fan to be always on whenever the machine is ... but I sure don't seem to be having much luck with that.

Any thoughts, input, and/or insights appreciated.

 

[MacUp72]

the pismo was a quite capable G3 machine back then, fanless..but a G4 is quite another thing heatwise. I guess you did some research on that mod and experiences with it before?
may try to get something like this working in the CD bay?

 

[herd]

Do you have AppleFan.kext? This might do what you want:

mac-classic.com/articles/mac-os-x-ppc-fan-control/

I'm sure there is probably 5v already available somewhere, like on the power board that the batteries plug into. I think the drive expects 5v. There is certainly 3.3v available, and a 5v fan should work with that and would make less noise at a lower speed.

If you slightly raise the voltage on the CPU it would probably be stable, even when hot.

If you drop the speed to 500MHz it would probably be stable, and cooler.

 

[GorfTheChosen]

the pismo was a quite capable G3 machine back then, fanless..

Just to be clear, the Pismo was never fanless so far as I know ... always had one.

And one could certainly do quite a lot ... without causing the fan to come on.

But that's likely due to the high temperature threshold Apple set before the fan would activate and turn on.

Like I said previously, despite that, I was able to make the fan come on (back in the day) with just the stock 500Mhz G3 processor when working the machine hard.

but a G4 is quite another thing heatwise.

Indeed.

I guess you did some research on that mod and experiences with it before?

Which mod ... replacing the G3 with a G4 ?

Or adding an additional fan/modifying the Pismo's fan so it's always on ?

If the former, it's a mixed bag ... some have complained about heat while at least one individual (LightBulbFun @ MR) has said he has his G4 upgraded Pismo clocked @ 600Mhz with no issues.

Of course no idea what all he was doing with it.

If the latter, I have attempted to research it but have found no evidence that anyone has done either mod (rewire stock fan to always be on or add an additional fan) ... although I did find one individual trying to locate a place to tap power from inside the computer to run his stock fan constantly.

may try to get something like this working in the CD bay?

That's a pretty slick gadget ... fan + ssd ...

Unfortunately currently unavailable (at least on Amazon), is for SATA (of course), and likely not designed to fit a Mac.

But your suggestion caused me to do a little further research and I came up with this:

KLIM Cool+ Metal Laptop Cooler with Vacuum Fan - New 2024

Price seems right ... even if the color is a little gaudy ...

Paint is cheap though.

Think I will give it a shot.

 

[GorfTheChosen]

Do you have AppleFan.kext?

Yes.

Will have to look at the values in my kext here though and see if they match what @greystash has posted there.

This might do what you want:

mac-classic.com/articles/mac-os-x-ppc-fan-control/

Possibly.

I'm sure there is probably 5v already available somewhere, like on the power board that the batteries plug into. I think the drive expects 5v.

Right.

I have identified the solder pads on the power pcb that the power connectors for the DVD drive and batteries connect to.

What I have not done is probe those pads with a meter while the computer is powered up to see which pads have what in terms of voltage, gnd, etc.

There is certainly 3.3v available, and a 5v fan should work with that and would make less noise at a lower speed.

Right.

It doesn't appear that it's going to take all that much cooling to get it run stably.

If you slightly raise the voltage on the CPU it would probably be stable, even when hot.

Yes, that remains a possibility.

If you drop the speed to 500MHz it would probably be stable, and cooler.

Right.

Actually though, I was thinking about raising it to 600Mhz if I can come up with a workable cooling solution ... as I have it on good authority that this particular processor will run at that speed ...

(That last line above is a bit of an inside joke)

 

[MacUp72]

..
Which mod ... replacing the G3 with a G4 ?
..
If the former, it's a mixed bag ... some have complained about heat while at least one individual (LightBulbFun @ MR) has said he has his G4 upgraded Pismo clocked @ 600Mhz with no issues.

ok, thats cool..from what I've read it depends very much on the individual sample of a G4 you have if you can push it that far..
not tried that.

.. although I did find one individual trying to locate a place to tap power from inside the computer to run his stock fan constantly.

that, additional fan inside the ( emptied) DVD drive, and when this works, maybe just add a little horizontal poti to turn it down or up.

That's a pretty slick gadget ... fan + ssd ...

Unfortunately currently unavailable (at least on Amazon), is for SATA (of course), and likely not designed to fit a Mac.

I'd look around a bit further because this solution seems doable. Of course this would mean:
- sacrificing the original CD/DVD drive
- but it does fit the best, also still ejectable ( could be an interesting theme for new ' Pismo DVD-fan-mod thread for sure)
- there is a 6V, maybe 12V tap in it for sure as the drive needs it.

that additional internal fan in the DVD bay doesnt have sensors obviously but wth..

But your suggestion caused me to do a little further research and I came up with this:

KLIM Cool+ Metal Laptop Cooler with Vacuum Fan - New 2024

interesting but a little bit too bulky for my taste
does this blow or suck?

stock fan, i looked it up.. sure I forgot the little fan on the left side, my bad





but to sum it up, in the end I dont know if an additonal internal fan solves your G4 heat prob, but it would be interesting to find out.

 

[GorfTheChosen]

I do have an extra DVD drive from the spare parts Pismo.

Might have to have a look and disassemble that and see if it’s practical to repurpose that as removable fan housing.

Would need to see if the incoming airflow could be routed to the processor card area.

Might well be possible to relocate the Ablecon IIDE——>MSAT drive adapter and SSD in there as well.

Would be an interesting exercise if nothing else.

As far as that Kilm cooler goes, it’s a vacuum unit.

 

[GorfTheChosen]

As far as that Klim cooler goes, it’s a vacuum unit.

Unless of course you position the unit such that it's exhaust is blowing into the Pismo's intake port on the right side next to the DVD/hdd bays.

It was delivered just a little bit ago and I have to say I'm fairly impressed. Feels pretty hefty, nice packaging.

Comes with 31" long USB-A ----> Barrel Connector power cable, 4 silicon rubber boots of varying width's that attach to the intake side to form a seal against the laptop (although as noted in the manual these may not even be necessary for the unit to be effective), a pair of double-side adhesive strips, a few pieces of die-cut high density foam blocks of varying thickness (not sure exactly what those are for), a sheet of various decals, user manual, and bonus ! ... a funny color-printed cartoon in multiple languages:



From peering inside the case through the exhaust vents the fan looks to be way oversized compared to the Pismo's stock fan and the airflow at the maximum setting is significant ... at least 3x - 4x of the stock fan ... if not higher.

The fan's speed can be manually controlled via a pot whose knob is topside on the case. Max rpm is a little over 3500 and it is rated to move 23.15 cfm @ full speed. While it is fairly quiet at full rated rpm, dropping the speed by 1,000 rpm makes it almost silent with a just a slight, low hum.

Lighted display is switchable to various colors (red, green, blue) and shows the fan speed and "real-time" air temperature coming out of the laptop:



With the Pismo in use as a render slave, where it just sits on the desk chewing away at jobs, I think this will be very effective at keeping things cool.

Time will tell as far as how well it holds up, but at <$10 it seems like a good value to me.