Overheating with k7xp, help needed

Hello there, im new in the forum and i got a serious problem, my computer is overheating since some time now and cant find the problem. My specs are:
Asus a7n8x bios 1.10(latest one)
AMD k7XP 2800barton not overclocked
2x kingston 512MB 333MHz DDR modules @ dual channel
ATI RADEON 9800PRO 128MB
Windows XP PRO with latest updates
Data Cooler water refrigeration system
I got all sorts of antivirus and anti spyware programs so that is discarded and ive updated my bios version 2 times since it started.
It happens some times and some others dont when i start the computer the temp goes to 50 ºC according to water system indicators, mobo ones and software programs and it goes up to 60 ºC at full load, the case is open and with some case fans and ive changed the power supply also.
Ive also tried to change the cooling system with a brand new one with copper heat pipe etc etc and the system is also overheating even more.
Please i need help. Sorry for my spelling as im from Spain and English is not my natural language and thanks everybody for the help

 

Both heatsinks were placed properly, i used titan silver grease with both of them and both were set to run at maximum speed all the time , checked it with software, bios and speed control.Downloading, thanks for the fast reply
By the way when i plugged the other heatsink despite its one of the top coolers and that ive checked it works on another computers my computer shutted down as soon as i tried to start it by overheat and bios resetted to "safe" values, something like 1100 Mhz at wich speed it could boot but at 70ºC, i can run the computer only with my water system and at 50 ºC and the normal temperature was 30 ºC at full load not idle. Those programs say my cpu is at 47 ºC and the processor diode is at 70ºC, if you need any info from them just tell me and ill copy it