Tuesday, July 1, 2008

Stock Mac Plus Temperature and Power Readings

Before I modify my Mac Plus, I wanted to get some baseline readings from the machine so that I would have something to compare the modified Mac against. Here are the results.


This was pretty easy. A watt meter showed an average of 31 Watts (.44 amps) spiking up to 34W and .46 amps when accessing the floppy drive.

Over 2 hours (non-idle, but no disk access) the power stayed at 31 Watts until the very last reading at which it rose to 32 Watts.

Turning down the screen brightness had very little impact. At full brightness my Plus used .44 amps, and at full darkness it used .42 amps.

Temperature Test

4 digital thermometers were used to monitor the Mac Plus. None were inside the mac. None were the same brand. An indoor thermometer sat near the Mac Plus, monitoring the ambient temperature of the room. The second thermometer sat on top of the mac, but it doesn't have a probe, just holes on the top meant to read indoor room temperature. I used this one to also get an idea of the temperature around the Mac. Third was a digital cooking thermometer with the probe laid across the vents on top of the Plus. Last, another cooking probe was inserted under the Mac (between case and desk).

Is this the best setup I could have used? Obviously better sensors could have been used... A thermometer inside the Mac would give a more accurate reading... But that's not all... Air-conditioning was starting and stopping during the test, and an oscillating fan was running.

I decided to go forward with the used method for a few reasons. One, and most important, it's what I could do, but in addition, I wanted to measure the success of the modification, and to me that meant results good enough to be detectable in a real world environment. If the modification's results aren't detectable with the used method, then it's not a successful modification in my mind.

Temperature Results

Included with this post is a graph of the temperature results. The graph was created with Cricket Graph (1987) on a Mac SE running System 6.0.5. The PICT image was converted to a PNG using Graphic Converter 3.8.1 on an iMac using System 9.

The results show a 13 - 20 degree (F) increase in temperature over 2 hours. The Mac Plus was running a simple screen-saver during the test.


With the baseline tests done, I can move forward with the modification. I would really like to see significant results in power usage and temperature. Fingers crossed.

I might see if I can get the next graph published without using the iMac, Graphic Converter 3.8.1, or System 9; all of which are newer than 10 years old. Maybe I will, maybe I won't.


arfinkatsjv said...

Nice, very scientific. Really, just because you didn't use expensive gear doesn't mean it's inaccurate by any means. I measures what you need and establishes the "control" for your experiments.

Looking forward to your "greets" demo again this year. Last years was good. (you did the talking moose, right?)

Equant said...

Thanks for the comments. No, I didn't do the talking moose, MacTV did. I did a boring Mac app where you clicked in a window and the names changed.