SiSoft Sandra cannot be right about this

sandra is saying my thermal resistance is .12, im using a vantec aeroflow hs i think and a coolermaster 60mm fan running at about 6750rpm. my crappy gemini cool block cracked...pic=http://interlab.gotdns.com:81/Overclocking/thermal resistance.bmp

its not it just guesses(ok so it doesnt guess it just doesn't do it properly since it doesn't know how many watts the chip puts out and I'm not sure which sensor it uses so for all realistic purposes it guesses) so its not accurate.

so then how is there anyway to actually tell what the thermal resistance is?