October 31, 2015: check of a micro-ATX alimentation FSP 350-60HLC (ATX format, 350W), and its replacement
See the ATX port configuration here
. Before pressing the power-on button of the computer, i.e. the equivalent of short-circuiting the PS-ON (green wire) and COM ports (black wire) with a conductor (see here
), there should be +5V on the 5VSB port. This is indeed the case when the ATX port is not connected to the mother board (5.04V); but it is no more the case when it is (4.35V). In theory the problem may come from both the alimentation and the mother board. However, the former seems to be more probable, as a sign of an alimentation that cannot provide the current anymore.
Moreover, when the PS-ON and COM ports are connected independently from the mother board, all voltages seem to be correct, and the alimentation of the fan turns correctly (though probably not enough fast). But when the ATX connector is plugged to the mother board and the power button pressed, all voltages are of the order of magnitude of 100 mV, and the alimentation fan remains at rest.
So I replaced this power supply with an FSP HEXA+ 500: after that it works perfectly, so the power supply was deficient.
Note that I have considered to replace capacitors individually as I have done on my ACER AL2216W internal power supply; but here it is more difficult, there is not much space to access components of the PCB.