Wesley's Tool-Box

• The Aftermath of Portable Athlon

After completing the world's first portable Athlon computer, it had been on a rather busy public relations charade for a while. It was even featured on SEK 2001, one of the biggest computer shows held in Korea. Here are some pictures.


The Portable Athlon was borrowing a booth of 'I Love PC', a popular monthly magazine in Korea.


Some teenage visitors were eagerly watching Portable Athlon running 3DMark2001 demo loop. Many thought that the demo was actually some sort of video clip, testifying the fluidity of the 3D rendering sequence. Clearly, no portable unit at that time had such prowess in 3D performance.


This is how the whole booth looked like. You can vaguely see the Lobby part of the demo running on the screen. By the way, the hanging drape on the bottom is saying that 'I Love PC' magazine is the 1st in both published and sold numbers among the computer magazines in Korea.

• Seeking True Mobility

So anyhow, I had thought that my goal of 'carrying a desktop computer anywhere and use it at will' was achieved with this unit. This had, unfortunately, not been completely met with success. First of all, this unit did not have any auxiliary power input, requiring 220V AC input (standard for South Korean power outlet since 80's) if I wish to use it. This isn't exactly a major problem, as, due to the relative size of the unit, it needs to be used on a firm surface like a laptop computer, and the usual places I carry it to does sport a power outlet. Then the actual weight and size became sort of problematic. A unit that goes for nearly 10kg isn't truly fit for easy carrying like a usual mobile gear, not to mention the whole rig was tightly packed in a backpack, making it sort of a hiking trip every time I carry it around.

That was okay, I thought, until my health saw a rather rapid decline. I had been hospitalized last August relating to my health conditions. Meanwhile, I had enlisted myself in the army, and I did enter the recruitment camp early September. However, because my medical conditions were ill-fit for military service, I was given a return-home slip within the week. I am listed as 'exempt' regarding military service since late November. This whole mess, while buying me some 26 months of time, left me with lots of concerns. One being that I can no longer do heavy work until my health improves back. My doctor told me that my condition can take forever to get better, so that's apparently not going to happen soon.



Let's push my gloomy personal business aside though, as the consequences of the past months simply meant that carrying my Athlon computer around was not as feasible as it once used to be in the scope of this article. This meant I needed to go back to the drawing board for another computer design.

• Installation and Benchmarking

Now it was time for the real test; to hook the air conditioner up to my system and observe temperature differences. System specification is as follows:

CPU:	AMD T-bird 1GHz @ 1.12GHz
M/B:	Soltek SL-75KAV (KT133A Chipset)
Heatsink:	Zalman CNPS3100-Gold
RAM:	256MB x 1 Corsair PC-150 SDRAM
Video:	LEOTEC GeForce2 MX 32MB
HDD:	IBM DeskStar 75GXP 30GB
OS:	Windows 2000 SP2
Else:	Classified ^_^

Tests were done in a stable ambient temperature environment for 40 minutes and MBM5 was used for temperature detection and logging. CPU was at 100% load during all times of the test using distributed.net client.

• Conclusions

Providing cold air to the intake fan of the system, the air conditioner should be lowering the system components overall. The result shows that it does indeed do that, as it lowered the CPU temperature by approximately 3C, which correlates to the dry run results. Although not shown here, the GF2 MX's chipset core experienced nearly identical temperature drop also. I believe the project has been a success! I think I can last this summer without much worries now.

• Designing and Making Housing

The housing was to be made in clear acrylic material like the previous project. To accurately create a housing for the air conditioner, I used a drafting program to create parts and virtually assemble them to see if there were any errors before actual work. My skills at using these programs improved since the last project mostly due to the fact that I'm taking classes about them in the university. Seeing that there weren't any problems to be found, I went back to my home town (Ulsan) to ask for the skilled help of the person who made the case for my Portable Athlon. Without much fiddling, he was able to exactly reproduce my draft into reality. Coincidentally, while this was being made, on the other side of the town, Confederations Cup 2001 preliminaries were being held at newly built Munsu Soccer Stadium. Korea won over Mexico 1-0 that night.

• Dry Run

The final product meatures 15.0 x 15.5 x 17.0 (cm). This fits in a small totebag, and it is quite possibly yet another 'portable' unit. With everything in order, I set out to find optimal operation point of this unit. Too fast an airflow, the cold side would not be able to put out cold enough air because of insufficient cooling time; too slow and the hot side would overheat. I found out that using 5V for the fan was better than 12V in this sense. Temperature drop against ambient was measured between 2.5C and 3.5C during the tests. Not spectacular, but when a few degrees of drop in temperature matters a lot in overclocking, it certainly didn't look so bad at all.

 

• Proto-Assembly and Testing

With key parts now in hand, I could now put them together for some preliminary testing. I was not yet certain if this could actually work, and the lab people did voice some concern about the possible failure, so I needed to see some solid proof. So I put the TEC in between the heatsinks and powered up.

The test went rather satisfactorily. The heatsinks distictly heated up or cooled down, and air nearby was affected by it. Unfortunately, it did not have a housing to put them together yet, and it sat around like this for a week.

• It Could Just Cool Air

I certainly wouldn't try the experiment again on my T-bird Athlon in my Portable Athlon unit for two main reasons, and that has to do with the TEC I have in question. Its power rating is 72W. A TEC can only pump heat up to about half of the power rating effectively, meaning the cold side has to have a load of less than 36W. A T-bird easily tops 50W in maximum power consumption, and that's one of the reason why it's not fit for use here. The other reason is that I have 150W power supply unit in the system, and it is already pretty much maxed out. You don't see a T-bird running on a 150W PSU every day anyhow. It has nowhere near the 72W power left to power the TEC.

Therefore, I decided to use the TEC to cool the air itself, in a fashion not so differently from an air conditioner. Thus was born the TEC air conditioning project. The parts I needed now: two massive heatsinks, some fans to blow air over the heatsinks, and a power supply to power both the TEC and the fans. I bought yet another 150W PSU to use for this project as you can see below. I did not want those big, conventional units, and I didn't want a long one like last time. So I got a microATX version. If you see closely, I attached a small switch on the motherboard connector so I could turn it on and off.

• Massive Flower Power!

As for heatsinks and fan, I needed not look further than Zalman Tech's heatsink laboratory. The people there are quite eager to help me out, so I asked if I could have some heatsinks for the air conditioning project. They told me that I could not use a conventional flower heatsink they make, because the end of the fins does not cover the 40x40(mm) surface area of the TEC fully and would not effectively cool it. They suggested making a modified cooler that would cover all that. Of course, it would need far more fins than usual. Two to three times more, in fact.

In the end, two massive heatsinks resulted, one in copper, one in aluminium. The fins spread out in near half-circle; the copper one has 135 fins, and aluminium, 145. The only downside to this is that the fins are too tightly packed together and might block good airflow. Nevertheless, it seemed good enough for the project, not to mention it's very eye-catching.