SinisterMessiah and
CmdPT, 57c in TAT or Core Temp is within the normal range, and CmdPT, 47c at 2.9 Ghz with 100% TAT is inaccurate, probably offset by - 15c. Your actual Core Temp is probably 62 to 64c, which is still OK. Please review the following topic for answers to your temperature questions:
Core 2 Duo Temperature Guide
Intel has 2 separate temperature specs with 2 different readings from 3 separate temperature sensors in the C2D. Keep in mind the 965 motherboards can display readings inconsistent with the norms. In this instance SinisterMessiah, your system is displaying incorrect values offset by - 15c in Core Temp, and reasonable values in TAT. Both programs read (and can miss-read) the same dual Thermal Junction sensors (Tjunction) within each core.
Further, Easy Tune 5 is incorrect, because it's not possible for your CPU case temp to be 18c, which is read from the single Thermal Case sensor, (Tcase), not to be confused with "computer case". 18c would be below normal ambient room temp at 22c, unless your ambient room temp is extremely cold. I'm inclined to think that Tcase is offset by ~ - 5c, so 18c idle would actually be ~ 23c, and 39c load would be ~ 44c. This would make sense.
Since Tcase tables are stored in BIOS, it's possible that a BIOS flash and chiposet driver update to the latest releases may correct these problems. Before you overclock, remember the boxed Intel cooler is marginal even for a moderate OC, so you may want to consider replacing it with a cooler suitable for handling an overclocked CPU with increased Vcore.
Hope this help. 8)