I imagine a cooling pad is about all you can do....

Though I don't think it was uncommon for Pentium notebooks to be fan free. I had a Dell Latitude PMMX notebook and I think it was passively cooled.

According to cpu-world.com a Socket 7 Mobile PMMX does/did exist. So, assuming I could find one and also assuming the motherboard will let me set the core voltage low enough, could I simply swap out the desktop PMMX for a mobile one? Or are there fundamental differences between the mobile and desktop versions beyond core voltage that makes a direct swap impossible?

I'm not sure if the CPU voltage would change. Whether that is autodetected or not.

Now that I look things up, I remember that my Dell Latitude had a Pentium MMX mobile module that uses the 2.45v of the mobile socket CPU you must be talking about.

The CTX EzBook 700 (At least the model I used to have) doesn't auto-detect the CPU. It has a bank of DIP switches on the motherboard to select these options. This is how I was able to drop the vcore and underclock the processor to reduce the heat output. I do not recall what the lower limit for vcore was, but if it does allow me to select a low-enough voltage, then theoretically I should be able to drop in a mobile Socket 7 PMMX (these supposedly did exist in addition to another one that used a different socket type). Am I correct? A quick search on eBay suggests these are unobtanium though while the 2.8v desktop versions are plentiful, so this could probably be a moot point anyway.

torindkflt wrote:

According to cpu-world.com a Socket 7 Mobile PMMX does/did exist. So, assuming I could find one and also assuming the motherboard will let me set the core voltage low enough, could I simply swap out the desktop PMMX for a mobile one? Or are there fundamental differences between the mobile and desktop versions beyond core voltage that makes a direct swap impossible?

They have different packaging. Check this one out:

I don't think what you suggest is possible.

RacoonRider wrote:

They have different packaging. Check this one out: http://i.pchub.com/i/Toshiba-Libretto-70CT-Main-Board-Motherboard-FLHSY3-B360 […]
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They have different packaging. Check this one out:

I don't think what you suggest is possible.

There appears to have been two different versions of Mobile PMMX, one using the slot-type socket in your picture, and the other with the die mounted on an adapter that plugs into standard Socket 7. Here's the info page on cpu-world.com I'm getting this info from: http://www.cpu-world.com/CPUs/Pentium/Intel-M … FV80503200.html

And here's (supposedly) a picture of a Socket 7 Mobile PMMX.

Like I said though, these seem to be made of unobtainium, so it's probably not even worth the effort to try finding one. This was more of an "is this possible" thought exercise and less of an "I definitely want to do this" endeavor.

Maybe this?

http://www.ebay.com.au/itm/Intel-Mobile-Penti … =item518f56964f

Although looks more like a standard desktop chip.

If the picture shown is for the actual items being sold, then most likely those are indeed desktop and not mobile. What seems to complicate matters is that Intel used the same part numbers for both the desktop and mobile versions, cpu-world has a disclaimer warning of this fact. So, it is certainly understandable if the seller has erroneously mislabeled these.

The heat dissipation of a CPU scales in linear proportion to clock speed but with the square of the voltage. So dropping the voltage is the most effective thing you can do to make it run cooler. Dropping the clock speed should mostly be seen as a way of enabling a lower voltage, as the reduced clock speed in itself isn't very effective but being able to lower the voltage makes it more profitable.

You could try to find a CPU that responds the best to undervolting, down to whatever voltage settings that board allows. I could only assume the 233 or 266MHz chips (did those come in socket-7?) to be the best undervolters, but I don't know if that's the case.

Maybe you can come up with some way of mounting a fan somewhere, or even install a CPU heatsink/fan assembly from a different laptop (might require epoxy). You'd need to find a power source somewhere in the laptop to drive it from. If you're only going to use the wall adapter, then the power input from that connector would be a candidate, depending what voltage it is of course.
However, if the main problem is heat affecting other components inside the machine, then it needs a case fan to evacuate the heat, not an internal CPU fan that will leave the heat still circulating in there.
I have no idea about the existence of fans for PCMCIA or drive bays. Perhaps some product like that is out there, but I never saw it.

Maybe there's some conceivable way of cooling the hard drive. If you adapt it to use a CompactFlash card, maybe they are more robust against heat or just generate less of it.

Does the laptop have a spare bay? Maybe a bay with hardware you don't need like an internal modem? Use a copper plate to replace the existing CPU plate and run copper pipe from it to your empty bay and install a fan and heatsink there.

It does not have a spare bay, the closest to that would be the PC card bay. It's sized for a Type 3 card, but IF (big if) I ever use it, it would only be for a single Type 2 card. So, assuming there is enough internal space to route the piping, that certainly is one option.

Or, I could try to find one of these...they did exist!

Though I don't think it was uncommon for Pentium notebooks to be fan free.

I imagine this was certainly the case for laptops equipped with mobile PMMX processors. The problem with the CTX is that they used a standard desktop-class PMMX, which really runs too hot for a laptop without a cooling fan, at the very least a better design on the passive cooling. Admittedly the processor itself seemed to handle the passive cooling just fine, but the excess heat of being crammed into a tight laptop case did ultimately prove fatal to the hard drive.

Yes, I certainly could use a CF card, and I will keep that alternative open. But, if possible, I would prefer to stick with a mechanical hard drive because that is what my original CTX had, and barring anything that ultimately proves dangerous to the longevity of the system, I prefer to keep my vintage reacquisitions as close to the original as possible.

Pics of the guts would help.

As for external cooling, some food for thought: http://www.makeuseof.com/tag/5-cool-diy-ways-laptop-cool/

I have several Pentium1 laptops that don't have their cooling fan spin. I think it's because they are CMOS battery controlled, can't find anything else. In my experience you will be ok as long as you turn off your laptop after each 1 hour of use at a time. Just give it a break to cool down and then power up again and have fun some more. I've also found that in laptops where you can change the cpu, try putting in a slower speed model and you will have longer usage time before cool-down breaks. Thats if you can stand downgrading the cpu. 🤣 Or just try replacing the CMOS battery or cooling fan.

Alright, I finally received the CTX. Here's a picture of the inside:

And here's a picture of the passive cooling plate located under the keyboard, flipped upside-down so you can see the side that contacts the CPU:

The bottom of the metal plate has a couple foam-type thermal pads that contact the CPU and chipset. The other side is just bare metal with nothing on it.

The (what I presume is a) heat pipe that runs off to the right doesn't connect to anything. There are no fans or radiators on the side of the system, or anywhere else for that matter. This metal plate is the only cooling in the entire system. As I said before this seems fine as far as the processor itself and motherboard goes, but the excess heat isn't able to leave the case quickly enough, and this overheating ultimately damaged the hard drive on my last CTX.

The switches on the motherboard to the upper right of the chipset control the CPU core voltage (2.5, 2.8, 3.1, 3.3) and clock speed (100, 120, 133, 150, 166, 200, 233). This is how I was able to underclock & undervolt my last CTX to help reduce the heat. I have already dropped the vcore to 2.5V. Even though the spec sheet for the desktop PMMX 200 says 2.65V is the minimum, it seems surprisingly stable at 2.5V and also was on my last CTX, so I have no qualms about running at the lower voltage unless anyone here can think of a good reason I shouldn't do so. But if possible, I would prefer to avoid underclocking for performance reasons. Granted, the difference between 166MHz and 200MHz may be minimal, but with my vintage re-acquisitions, I'd like them to be as close as possible to how the original was at the time I first received the original (My OCD is already throwing a minor fit over the fact this CTX has a different GPU than my last one 🤣). This is also why I would like to stick with a mechanical hard drive instead of switching to CF or another form of SSD. I mean I ultimately will if I absolutely have to, but I'd prefer not to for nostalgic accuracy.

If there's really nothing else that can be done to the laptop itself, that's understandable. I did manage to find one of those PCMCIA cooling fans on eBay, I'll know in seven hours if I'm getting it or not. If I do, I imagine it'll help as well.

torindkflt wrote:

... The bottom of the metal plate has a couple foam-type thermal pads that contact the CPU and chipset ...

I'd replace the foam pads with copper plates/shims, plus quality thermal paste.

Another option is drilling holes or cutting slots at the bottom of the laptop case, this way convection would suck in cool air from below and expel hot air up thru the keyboard.

..

Even better if the laptop has 'feet'. This is as ghetto as they come, but works: https://www.youtube.com/watch?v=N9Gc4PHFBQg

I have a tube of AS5...somewhere. But it's coming up on ten years old. Does that stuff have a shelf life, or would it be good still? As for the copper shims, I'll have to see where I can get some.

As for feet, it doesn't have any, but I could very easily add some by sticking a couple of these wire clips to the rear bottom:

These things work perfect for replacing broken feet on keyboards, so I imagine they'd work on a laptop too! 🤣

Just squeeze the AS5 tube and if it still flows and remains sticky it should be OK.

Anything that lifts the laptop and widens the air gap below it will be beneficial for cooling.