Found this, which may be of some help:
# No Post and fan doesn't come on when the computer is switched on: First check to see if the CPU fan comes on, if it does you probably just have a bad power supply fan, unfortunately you can't replace it you'll just have to exchange the one you have for one that works. Next make sure that the power cord is plugged into the back of the unit and into the wall. Then ensure that the power switch is connected to the case and power supply and seems to be functioning correctly. If none of these suggestions work then you probably have a bad power supply. If this is the case DO NOT TRY TO REPAIR IT. There are definitely no user serviceable parts in the power supply. You will just have to return the power supply and/or case for one that is functioning properly.
# No Post and no sound from the speaker (condition beeps) but power comes on: There are a couple of possible causes for this. First look to see if the CPU fan comes on, if it does it probably means that the power supply is good and it is a construction or component problem. Next make sure that all of your power connections are correct and data cables are connected properly. If you're sure that they are then you need to make sure that your RAM and CPU are seated correctly. If they are you could possibly be looking at a faulty part (motherboard, RAM, or in rare instances CPU). The first way to test this is to disconnect all of the external components except the motherboard, CPU, RAM, video card, and power connections. That means disconnect any additional cards you may have installed, and any data cables from drives to the motherboard. Then try switching the machine on again and see if it POSTs, if it does you either have a bad secondary component or had one of the components installed improperly. If it doesn't remove the video card and try again, but this time you'll have to listen for the condition beeps from the internal speaker (just check your manual for the beep codes). If you still have no response and you have access to another computer try the components in that system if they work you know its either a bad motherboard or improper installation. If you can't do this you'll just have to assume one of the key components (RAM, CPU, or motherboard) is bad and exchange them for good ones.
http://hansworse.freeyellow.com/trouble.html