Temperature of Radeon 4870

I would like to know how high I can take the temperature of my 2 radeon 4870 in crossfire and how to adjust the fan because someone argued that fan of these cards are only limited to 20-25% of their capacity in order to not to make too much noise. Thanks in advance

Download Cpu-z it will adjust the degree of your graphic card but for the fan the speed test can change only if the temperature drops

Or you can download Atitools as well