how accurate is systool for measuring temps?

[locutus12]

i only ask because my bios said my CPU was 45oC and that was @ idle, yet systool in windows is telling me that my idle temp is 37oC i dont know what to believe... i have done some heavy overclocking today so im worried about overheating the CPU (got an extra 680Mhz out of my venice )

 

[locutus12]

currently using a vantech Mach 1 cooler, its not widely used but is quite good, may need to strap a better fan on it though...