It's a generic Asus mobo, G31 chipset. This is under 3 min of prime95 testing.. It shows the CPU is idling at 63some degrees upon powering the PC up. BIOS shows 60ish.
I have changed the thermal compound, the cooler itself seems like a chinese low-quality generic one, but it's not shy of a standard OEM cooler size. Not sure if it makes good contact tho, as the heatsink doesn't get hot, regardless of what the temp readings show. It's the backplated type, I have screwed it tightly, can attach some pictures if needed.
Could it be that it's reporting the temperatures wrong? Having in mind it's a s775 board that wasn't originally intended to work with a s771 CPU, that's the only thing that comes to mind..
Here is a CPU-Z validation for the mobo itself; http://valid.x86.fr/rg8x7t
Small edit; I bought the PC a day ago, so I have no idea if it ever reported normal temperatures.