I went to use my computer last week and it's usually left switched on but this time it was off. I tries the switch to no avail and I checked all the connections and they were fine. I assume it's either the power supply or the mother board. Is there any way to check or am I just better off taking it in to get fixed? Cheers.
Sounds like the power supply - do you have a old PC with a spare PSU that you could wack in to test it??
Don't worry about that for now, you don't need the drives connected for the machine to POST and come up with the BIOS boot screen. As long as its powerful enough for the parts in your system, and so long as it has all the correct connectors (which it may or may not depending on the age, power supplies made prior to 2005 will usually have a 20 pin ATX connector, rather than the 24 pin connectors used in most systems today, and power supplies made prior to 2002 will not have an ATX12V connector (the smaller 4 pin connector with the yellow and black wires that is separate to the main ATX connector)
I don't think I could have said that better!! Only other thing I might mention, make sure everything is plugged in internally..
Sounds like PSU, but.... take the ATX connector off from the motherboard, grab a paperclip and put it into the green and any of the black earth wires. This should turn the psu On, and you can put a multi meter on the other pins to check if its live, or just ensure that the psu is ON ( see if the internal fan is spinning). Also, many motherboards have internal power buttons on them, mine does (power + reset). try hitting one of these to see if it powers on.
My guess is PSU, though it could be both. I.e, PSU blows and then takes mboard with it, I've had that before.