I have Sony VAIO F13Z1R laptop with GeForce GT 425M.
Under all versions of Ubuntu (12.04+) it is hot, while using
xserver-xorg-video-nouveau driver.

> sensors
acpitz-virtual-0
Adapter: Virtual device
temp1: +70.0°C (crit = +98.0°C)
temp2: +70.0°C (crit = +98.0°C)

nouveau-pci-0100
Adapter: PCI adapter
temp1: +70.0°C (high = +95.0°C, hyst = +3.0°C)
                       (crit = +105.0°C, hyst = +5.0°C)
                       (emerg = +135.0°C, hyst = +5.0°C)

coretemp-isa-0000
Adapter: ISA adapter
Core 0: +70.0°C (high = +84.0°C, crit = +100.0°C)
Core 1: +70.0°C (high = +84.0°C, crit = +100.0°C)
Core 2: +70.0°C (high = +84.0°C, crit = +100.0°C)
Core 3: +70.0°C (high = +84.0°C, crit = +100.0°C)


For logs see
https://bugs.launchpad.net/ubuntu/+source/xserver-xorg-video-nouveau/+bug/1196049.