I have recently installed Xubuntu 12.04 alongside Windows Vista on my Acer Aspire 6920G laptop. I installed the latest proprietary fglrx drivers for the ATI radeon mobility 3650.
In Xubuntu I felt significant heat coming from the area in which the graphics card is situated, even when the system is idle. After about 10 minutes of playing Quake Live the system shut down suddenly. I opened up the laptop and found that the reason for the emergency shut down was most likely the graphics card, as the heat sink was extremely hot. The heat sink for the CPU wasn't hot and I vacuumed it recently (and temperatures are within normal range) So I have assumed it isn't the CPU.
I vacuumed the laptop again and booted into Windows. When the system is idle the laptop feels warmish but significantly cooler where the graphics card is situated. After playing UT2004 and Quake Live for a good while I found that even though the graphics card got warmer, the computer never shut down.
Has anyone else had this problem and does anyone know why the graphics card overheats in Xubuntu and not Windows (if that is indeed the cause)? How can I find out what exactly is causing this problem? is it a power-management issue or graphics drivers issue? I installed Xubuntu to have a less resource intensive system but I might have to go back to Windows for fear of overheating and emergency shut downs.
One thing I also noticed was that UT2004 runs with lower frame rate and has to have less demanding graphics settings to run more smoothly in Xubuntu. In Windows I can have very high graphics settings and it runs very smoothly. So perhaps the route of the problem is the drivers. However, the fan/system-in-general seems much noisier in Xubuntu, even when idle, although the CPU usage doesn't seem any higher.