the thermal properties is measured by watts, they usually listed on the spec.. (TDP / Thermal Design Power)
example : (to be updated)
pii 955 BE has TDP 125watt
quoted from cpuworld (this is for Processor but it also same with GPU)
"The Thermal Design Power (TDP) is the average maximum power a processor can dissipate while running commercially available software. TDP is primarily used as a guideline for manufacturers of thermal solutions (heatsinks/fans, etc) which tells them how much heat their solution should dissipate...."
so would the cooler that I posted be a good cooler for a 7870 GHz Edition?