Questions on buying an under-laptop cooling fan

[blm]

Last month I bought a gently used R51 Thinkpad. Who makes a durable, quiet cooling fan to put under the laptop?

I understand that some of these purchased cooling fans suck the heat from the laptop while others blow cooler air at the underside of the laptop. Is one better than the other? [Not knowing, I'd guess that the kind that blows air to the laptop's underside would help the built-in laptop fan rather than fighting it by working against the built-in fan. Yes? No?]

When I use my laptop, I put 4 pill bottle caps on a table or desk top and then put the laptop on the caps so there's more air under the laptop. Is doing this almost as good as (or maybe just as good as) using a purchased cooling fan (such as one from Antec) under the laptop?

If you recommend some purchased cooling fan, what make and model for durability and quiet running?


Thanks

[AMATX]

Best Buy - Belkin brand, $20-30. Centrally located fan, blows air on underneath side of the laptop.

Don't know anything about other brands, what's good, what's bad.

This one, though - cheap, works for me.

[virge]

There's a short discussion on cooling pads here: http://forum.thinkpads.com/viewtopic.php?f=28&t=87558

[eyestrain]

The R51, especially if you have a Dothan chip (2M cache, not 1M cache. Pentium 715 or better) is a very undervoltable computer. If you haven't tried undervolting yet, you might be surprised how much cooler&quieter the computer runs. You can use NHC or Rmclock to undervolt. Here's a huge thread about undervolting with NHC:

http://forum.thinkpads.com/viewtopic.php?f=27&t=28482

A lot of the complication is in trying to add fan control and undervolting at the same time. If you just want to undervolt to make it run cooler, you don't need that. Unless you want to add fan control to force the fans to cool the computer even more than undervolting alone.

If you're lucky, NHC will work perfectly, easily, the first time you try it. (Some people have trouble.) Finding the best voltages can take a while though. I use Prime95. Faster if you focus on the lowest and highest voltages, and roughly estimate the middle ones conservatively.

The pill bottle caps sounds like it should work ok, as long as it is stable and comfortable, the way you use the laptop.

I like to use aluminium cookie sheets. Some people use cooling trays, wires with spaces between them. Aluminium carries away some heat.

I've even used aluminium pots turned upside down. But for long term, a nice aluminum tray is better, especially one with ventilation of some kind.

I don't like the ones with fans, because of noise. I'm sure a well designed one would work better than just providing air circulation, or a tray, but don't know if it's enough to be worth it.

[blm]

The R51, especially if you have a Dothan chip (2M cache, not 1M cache. Pentium 715 or better) is a very undervoltable computer.

I'm not using the laptop at the moment. I'll have to try to find out later if I have the Dothan chip.

If you haven't tried undervolting yet, you might be surprised how much cooler&quieter the computer runs. You can use NHC or Rmclock to undervolt. Here's a huge thread about undervolting with NHC:

http://forum.thinkpads.com/viewtopic.php?f=27&t=28482

I don't have Windows in the R51. I installed a Linux distro (MEPIS 8.5) as the sole OS. Maybe there's some Linux software that does what the Windows software does.

A lot of the complication is in trying to add fan control and undervolting at the same time. If you just want to undervolt to make it run cooler, you don't need that. Unless you want to add fan control to force the fans to cool the computer even more than undervolting alone.

So "undervolt" means using less voltage than necessary. Is that correct? [This is a term new to me.] How is it done?

The IBM-made AC adapter (handed to me by the salesman just before I was about to pay for the gently used R51) says it's output is 16V and draws 4.5A. Is that the standard for IBM laptops or just for my R51? [I've run the R51 from house current but the other day I forgot to flip the power strip switch so the R51 ran on the battery. As I recall, it wasn't running long when I heard beeping that I realized was telling me the battery would soon be dead. So I then noticed my failure to turn on the power at the power strip. I suppose the rather early beeping means my R51 battery is nearly shot. Yes? No?]

Earlier today (before you must have posted your useful comments and help to this forum) I ordered an aluminum laptop stand/cooler which has a fan that can be placed in various locations on the back of the perforated aluminum plate. It's the CRF104 XL shown here: http://www.cradia.co.kr/crf104xl.html It cost as much as the plastic Belkin one having a single fan fixed in place.

The pill bottle caps sounds like it should work ok, as long as it is stable and comfortable, the way you use the laptop.

Yes, the caps are all the same size and height and I only used them on a table top or desk top, so this was a stable set-up.

I like to use aluminium cookie sheets. Some people use cooling trays, wires with spaces between them. Aluminium carries away some heat. ......But for long term, a nice aluminum tray is better, especially one with ventilation of some kind.

Good ideas.

I don't like the ones with fans, because of noise. I'm sure a well designed one would work better than just providing air circulation, or a tray, but don't know if it's enough to be worth it.

Yes, I hope the fan is quiet.

[eyestrain]

The adapter sounds like the right one. I'd fully charge the battery and see how long it lasts. You can also probably see info about the battery in your Linux distro, but I don't know about your distro in particular. You can see % of capacity available. Maybe in Power settings area.

So "undervolt" means using less voltage than necessary. Is that correct?

Well, without undervolting, you use more voltage than necessary. Intel isn't going to bother carefully testing each CPU to see how low the voltage can be. And laptop manufacturers find it easier to just have one specification per processor. Where in reality, each individual CPU from the factory has different tolerances.

Undervolting, you reduce the voltage supplied to the CPU, reducing heat, power consumption, and noise. And potentially increase component life, especially if you can keep temps as or more consistant than without undervolting.

If you appropriately test, to be sure that you haven't gone overboard and reduced voltage too much, then there is no downside I've ever heard of. If you don't test, and go too low, your system becomes unstable, either crashing right away, or if you barely crossed the line, crashing once every many hours or even days. But it's easy to avoid that by testing. There's plenty online about this.

With Linux you can use PHC instead of NHC. I haven't got it working yet, but I'm a Linux newb.

The Win tools might be easier, so if you get PHC up, and start to undervolt the first freq of your chip, then you might want to switch to windows to find the voltages for your cpu, and then back to Linux to put the data into PHC.

Even if you have a Banias CPU, it is still very worth undervolting. Dothans are usually even better, and in my limited experience, easier to test finding the lowest voltage.

All Pentium M's have the potential to undervolt to .7V at their lowest frequency. (If yours doesn't, you're unlucky.) Intel raised that # quite a bit with the next set of chips. So your Dual Core chip "could" undervolt but Intel won't let you (much) except at high frequencies.

When doing something with lots of idle time and bursts of activity, like surfing, Pentium-M undervolting can show very good results, unlike Core chips.

I suppose if you got rid of almost all "wakeups" then you might not need to undervolt your lowest freq, but that's another story.

[GrandMasterKhan]

IF the cooling sys is designed to pull air in and you get a pad that does the opposite you are defeating the thermal design of the chassis and cooling system within the NB. While such contraptions might cool the surface ie the bottom of your NB, they could actually harm the planar. You might think your NB is cooler based on surface temps. IF the manufacturer felt the cooling system as shipped is adequate then you should accept their design engineering. Are you know knowledgeable about cooling systems than they are?

[blm]

IF the cooling sys is designed to pull air in and you get a pad that does the opposite you are defeating the thermal design of the chassis and cooling system within the NB. While such contraptions might cool the surface ie the bottom of your NB, they could actually harm the planar. You might think your NB is cooler based on surface temps. IF the manufacturer felt the cooling system as shipped is adequate then you should accept their design engineering. Are you know knowledgeable about cooling systems than they are?

For the cooling system I got today -- see http://www.cradia.co.kr/crf104xl.html -- the fan can be put anywhere onto the back of the perforated aluminum plate and the fan can be attached anywhere so that it either blows air onto the back of the laptop *or* draws warm air from the back of the laptop. I'll always use the former mounting.

What's the "planar"?

[vanaya]

That is a pretty sweet stand/cooler. "Planar" is another name for Motherboard.

Definition of: planar

A technique developed by Fairchild Instruments that creates transistor sublayers by forcing chemicals under pressure into exposed areas. Planar superseded the mesa process and was a major step toward creating the chip.

[blm]

That is a pretty sweet stand/cooler. "Planar" is another name for Motherboard......................

Thanks for both vanaya.

And the fan is extremely quiet.

[Navck]

For the cooling system I got today -- see http://www.cradia.co.kr/crf104xl.html -- the fan can be put anywhere onto the back of the perforated aluminum plate and the fan can be attached anywhere so that it either blows air onto the back of the laptop *or* draws warm air from the back of the laptop. I'll always use the former mounting.

http://www.coolermaster.com/product.php?product_id=6612
I happen to have a similar product, which I use mainly in bed. Works great for standoff.

[Mike Blake]

When I use my laptop, I put 4 pill bottle caps on a table
or desk top and then put the laptop on the caps so there's
more air under the laptop.

Wow, thought I was the only to come up with that trick! I don't feel so alone anymore...