The green light illuminating only shows that there is "some" power getting to the MB and
the amber light on the power switch working erratically may suggest the psu is faulty/dead.
The loud noise may have been the fan on the psu failing and with it being left on overnight
it has possibly overheated, as I suggested I would not do any more testing with the FSP psu
attached it is too risky, remove it and try a known good one.
There is no conclusive way of testing a psu without it being under load and without the right
equipment so it is a job best left to a suitably qualified person, you can however test the
psu yourself to see if is at least capable of switching on, you can do this by shorting the
green and a black connections on the 20/24 power connector, do this after you have removed
the psu from the case, I have attached a link to guide you through the procedure; http://www.smpspower...rs-pinouts.html
Below is the canned text of Digerati regarding psu testing;
To properly and conclusively test a power supply unit (PSU), it must be tested under various realistic "loads" then analyzed for excessive ripple and other anomalies. This is done by a qualified technician using an oscilloscope or power analyzer - sophisticated (and expensive) electronic test equipment requiring special training to operate, and a basic knowledge of electronics theory to understand the results. Therefore, conclusively testing a power supply is done in properly equipped electronic repair facilities.
Fortunately, there are other options that are almost as good. I keep a FrozenCPU Ultimate PSU Tester in my tool bag when I am "in the field" and don't have a good spare power supply to swap in. While not a certain test, they are better than nothing. The advantage of this model is that it has an LCD readout of the voltage. With an actual voltage readout, you have a better chance of detecting a "failing" PSU, or one barely within specified ATX Form Factor Standard tolerances. Lesser models use LEDs to indicate the voltage is just within some "range". These are less informative, considerably cheaper, but still useful for detecting PSUs that have already "failed". Newegg has several testers to choose from. All these testers contain a "dummy load" to fool the PSU into thinking it is connected to a motherboard, and therefore allows the PSU to power on, if able, without being attached to a motherboard - great for testing fans, but again, it is not a true load or suitable for conclusive testing.
Swapping in a known good supply is a tried and trued method of troubleshooting, used for years even by pros. If you have access to a suitably sized, spare power supply, carefully remove the suspect supply and replace it with a known good one and see if the problem goes away.
I do not recommend using a multimeter to test power supplies. To do it properly, that is, under a realistic load, the voltages on all the pins must be measured while the PSU is attached to the motherboard and the computer powered on. This requires poking (with some considerable force) two hard and sharp, highly conductive meter probes into the main power connector, deep in the heart of the computer. One tiny slip can destroy the motherboard, and everything plugged into it. It is not worth the risk considering most multimeters, like plug-in testers, do not measure, or reveal any unwanted and potentially disruptive AC components to the DC voltages.
Note the required voltage tolerance ranges:
And remember, anything that plugs into the wall can kill. Do not open the power supply's case unless you are a qualified electronics technician. There are NO user serviceable parts inside a power supply.
Thanks to Digerati
for the above information.