How Hot Is It?--GeForce2 in a Cube

On July 10 we posted a note on installing a GeForce2 MX graphics card from a Power Mac G4 into a G4 Cube. The GeForce2 MX replaced the stock ATI Rage 128 Pro graphics card. If fit perfectly and we compared their speed with a variety of tests. The GeForce2 MX bested the ATI Rage 128 Pro in most tests but mostly by only a small amount. The big exception was the frame rate of the 3D game Quake III Arena where the GeForce2 MX got 45 fps vs 21 fps. Q3A was run at 1024x768 resolution with high settings except for sound.

We were concerned about the possibility of excessive heat from the GeForce2 MX because it comes with a smallish heat sink in the Power Mac G4 533DP that it was pulled from. The BTO GeForce2 MX for the G4 Cube has a much larger heat sink. Indeed, Gauge Pro reported 57 deg C for the CPU when using the GeForce2 MX, 11 deg C hotter that when using the ATI Rage 128 Pro. We decided to explore the issue further since other web sites have recently posted this switcheroo.

We bought an indoor/outdoor thermometer from Radio Shack. It has a thermister on the unit and another at the end of a cord. To measure the heat generated we placed the unit on the main grill in the center of the top of the G4 Cube to measure the rising heat. We placed the remote thermister in the middle of the grill in the back of the Cube's top. The thermometer measures the current temperature and records the maximum and minimum over time from both thermisters.

Three tests were run with each graphics card installed: (1) the QuickTime movie of Steve Jobs' Macworld NYC 2001 keynote address was played twice (>4 hours) using Mac OS X; (2) The Quake III Arena v1.17 demo 1 was run 6 times; and (3) Quake III Arena was played on line for exactly 30 minutes. We enjoyed the last test the most, of course. Here are the results in degrees Fahrenheit:

Air Temperature (deg F) from Front/Rear Grills

Test	GeForce2	Rage 128 Pro
Play QuickTime Movie	107/116	110/112
Play Quake III Arena Demo 1	107/115	95/109
Play Quake III Arena On Line	118/125	98/115

The air from the rear grill over the graphics card definitely gets hotter than from the main stack. The NVIDIA GeForce2 MX produces more heat than the ATI Rage 128 Pro except from the main grill during the QuickTime movie. However, the temperatures do not seem particularly excessive in relation to the temperatures produced by ATI's card. Temperature utilities reported that our PowerBook 2400c frequently reached temperatures in excess of 160 deg F with the original 180 MHz 603e CPU. But the measurements are not comparable. We will continue to use the GeForce2 MX in our G4 Cube until we encounter some signs of heat distress.