The P4C800E NB does run at 50C with out active cooling .
I have made a patent , with an old P3 socket 50mm Fan , plus a tube cover 50mm , from a PHILIPS oil spey .
I had to cut all the fins at the same size, than the lower ones in the ASUS heat sink, i left uncut only the two large in the sides .
If you get all the parts together, the assemply is easy , the fan ties with the one side of the cylinder with two small plastick wires tiers (legran) .
The othe side just gets in to the heatsing , by 0.5 cm , and stucks there .
Its easy ,and effective, at the minimum cost .
You need some tools ,and a bit of skill , other than that its easy to do .
Now my NB temps is like 35 - 38C at max , with 29C room temp.
I had add permanent thermal sensor on the NB , conected on the P4C800E , third, external sensor plug.
Its located next to the jumpers about power switch - speaker etc etc