Notebook Trio: ASUS A8JS and G2P and ABS Mayhem Z5

Power Consumption

Related to the battery life discussions we've just finished, we have power and temperature results. For power testing, we removed the battery from the laptops and measured system power draw at the wall outlet using a Kill-A-Watt device. All three laptops were configured to run at maximum performance when plugged into AC power. We tested several different scenarios to try to isolate the power draw of the various components. First, we have the baseline measurement when the system is idle and sitting at the desktop. No applications are running for 10 minutes or more and the screensaver and hard drive sleep mode are disabled. As a CPU load test, we run two instances of Folding@Home at 100%. Finally, for maximum power load we leave the two folding instances running and start 3DMark05. In this way, we can see roughly how much power the GPU is using in 3D mode versus 2D mode.

System Power Draw (Watts)
	ABS Mayhem Z5	ASUS A8JS	ASUS G2P
Idle	44-49	26-32	43-52
100% CPU	67-71	47-52	71-81
Maximum	100	71	97

A few interesting things become apparent when we look at the power numbers. First, the beautiful, bright display on the G2P definitely contributes a lot to the high power draw. The power ranges listed above are for setting the displays to minimum and maximum brightness. The Mayhem Z5 and A8JS have a 4-6W difference in power draw when going from minimum to maximum brightness, while the G2P difference is 9-10W. Also worth noting is that at minimum brightness levels, the G2P remains brighter than the other two at minimum brightness.

Given the differences in LCDs, it's difficult to say exactly how much power is being used by the LCD and how much is being used by the graphics chips in the various laptops. Obviously, the ASUS A8JS requires the least power, but that makes sense considering it has the smallest chassis/LCD. The GeForce Go 7700 in the A8JS appears to draw a bit more power than the Radeon Mobility X1700 in the G2P, but as the 7700 performs better in games the additional 2W difference at maximum load vs. 100% CPU load could just as well be coming from other areas besides the GPU. What's particularly surprising is that the G2P uses almost as much power as the Mayhem Z5 at maximum load, despite running less than half as fast in most games at comparable settings. With a 100W maximum power draw, however, it's not at all surprising that the battery life during gaming on the Z5 can be less than an hour. Again, note that the maximum brightness of the G2P LCD is reduced when in battery mode, which is why battery life is still quite a bit better than the Z5.

Heat

Similar to the power testing, we checked the temperatures of the laptops. However, as we're more interested in a worst-case scenario, we only recorded temperature results for the maximum load scenario described above (3DMark05 looping for at least 30 minutes with two Folding@Home instances). We measured temperatures across the bottom of the system as well as on the keyboard and palm rests. Graphs don't do a good job of conveying this information, so we've used a table instead.

Surface Temperatures (Min-Max in Celsius)
	ABS Mayhem Z5	ASUS A8JS	ASUS G2P
Palm Rest	27-33	25-32	23-31
Keyboard	24-35	31-36	27-39
Bottom	27-43	25-39	24-44
Exhaust	39	46	44

It might be surprising at first that the ASUS A8JS is the warmest of the three laptops. Considering that it packs quite a bit of performance into a smaller chassis, however, the result is not entirely unexpected. We should also note that the ABS system tends to generate slightly more noise than the other two systems, although the fan noise from any of the systems never broke 35 dB at a distance of 24 inches. If you return to the earlier images of the system internals, you can see that the heatpipe and cooling arrangement on the Mayhem Z5 appears to be quite effective in dealing with all of the generated heat. The fan intake is much larger on the Z5, as is the exhaust, and the net result is that it is actually not really any warmer than the other two laptops. We should note that the bottom of the Mayhem Z5 was consistently warmer than the G2P, so while the G2P had a few hotspots and the rest was relatively cool, the Mayhem was 31-35° across most of the bottom.