To measure gpu temps, use a program called gpuz - http://www.techpowerup.com/gpuz/
Link to download: http://www.techpowerup.com/downloads/SysInfo/GPU-Z/
As far as cpu temps, that should be listed in your bios.
If you want an external method, you will have to buy some temp sensors. many fan controllers like the ones nxzt sells have temp sensors.