Phase IIb - Jet-Dry

New Data Aug. 5

I've read the discussions on Mike's Water Cooled CPU page about Jet-Dry and Rain-X as additives to improve the flow and performance of the water in liquid coolers. Well, I got a request from Mike who asked for some empirical data so I gave it a shot. I couldn't find any Rain-X but it turned out that I wasn't looking in the right places. I bought a small bottle of liquid Jet-Dry and put it to the test.

For more information on the Rain-X/Jet-Dry debate please refer to Mike's site.

The procedure for collecting this data was to allow the CPU temperature to fall to its lowest value and then measure it, and the water temperature, every 10s for an hour or more.

One possible source of error is the fact that my post Jet-Dry testing occured with an already warm (85F+) water supply. I'll have to run it again with the same initial conditions.

Rate of Water Temperature Increase
  CPU Water Delta Voltage
Pre Jet-Dry 0.00118F/s 0.00231F/s 0.00113F/s 2.8V
Post Jet-Dry 0.00076F/s 0.00124F/s 0.00048F/s 2.8V
Post Jet-Dry 0.00002F/s 0.00028F/s 0.00026F/s 2.5V

Note: My temperature sensors are very hires but the accuracy is only 0.5C (0.9F). Since we're only talking about a few degrees over several thousand seconds the data I collected is mostly noise. The pre jet-dry data was averaged over 4000s and the post was over 9000s.

Jet-Dry: Before and After

In this graph you can see that the post Jet-Dry CPU temperature is lower than the pre Jet-Dry CPU temperature. You can also see a small but measurable faster rate of water temperature increase after adding Jet-Dry. This was the predicition. These graphs suggest different conclusions from those of my previous data. The post Jet-Dry graph data was collected with the same initial conditions as the pre Jet-Dry data.

So, What does all of this mean?

The new data does suggest that the Jet-Dry that I added to my water supply did infact improve the performance of my water cooler. The fact that the water's rate of temperature increase was greater than it was before adding Jet-Dry suggests that the rate of heat transfer from the liquid cooler to the water is higher. This was the prediction. The bottom line is the fact that the CPU got 5-6F colder after adding Jet-Dry.


All images and data Copyright 1998 Larkin Lowrey