Last month there was a article about AMD's FS1B SoC dubbed AM1.
I enjoyed reading this, and actually went out and built myself a cheep HTPC using the AM1 5130, MSI AM1I mobo, and 8gb of ram.
The only thing that MaximumPC did not do for us is test these APU's without a cpu fan....
Well i have done just that.
when setting up system i used the stock thermal paste, heatsink and fan, with this setup the APU idled at around 10°C when under full load with Prime95 it hits and stays approx 25°C
Now when you remove the fan from the heatsink The temps start to rise rapidly up to AMD's Thermal Max of 76°C.
if you place a small fan in front of mobo, that blows across the ram slots and the APU heatsink the temps will stay at 15-20°C while idling and they top out at 52°C under load with Prime95
Now i am running this system on a open air bench, the fan i placed infront of my mobo is a 60mm x 10mm 1750 rpm TPM fan (stock fan from AMD FX4100 Black Edition), but with this in a case, and a case/PSU fan postioned correctly you should be able to run this just fine with minimal fan noise.
Remember AMD states that the Max Sustained Temp for this APU is 76°C, and is most likely the same for all 4 of the AM1 APU's
Hope This is Enlightening