Computer won't power up

[rsdofny]

I have a M9400z  computer.  Within the last 7 days, there were 2 occasions that the computer won't start immediately.    The green light was on near the power supply.  When I unplugged it and plugged it back on, the green light did not light up.  I unplugged the machine and opened up the cover to let the air in.  I played around with the voltage selection slightly the first time.  After a while the machine came back on.  Over the weekend, I cleaned up the CPU fan to make sure the ventilation in the computer to be good.  The computer acted up again this morning.  I played around with the voltage selector again, back and forth between 230 and 115.  I could power up the computer again. 

I suspected the problem might be due to cooling.  When it happens again so soon, there may be more problem.  Can it be the power supply?  How can I isolate the problem?  If it is the power supply, I think that I need to replace it immediately before it damage the rest of the system.  Where can I get the spare parts?  

[TheOldMan]

If the green light is not on, then the power supply is suspect.  This page says it is 350watt: http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01570964&tmp_task=prodinfoCategory&cc=us&dlc=en...

I would check the phsical size to see if it is a normal ATX case size.  If it is, then just replace it with a 400watt or better.

[rsdofny]

Does anyone know how to get hold of the parts number for the power supply for M9400Z?  And if there is any pdf file on how to replace the power supply?  Thanks

[TheOldMan · Accepted solution]

Here is the manual for that computer, but nothing on the powersupply: http://h10032.www1.hp.com/ctg/Manual/c01457519.pdf

Here is the parts page: http://h20141.www2.hp.com/Hpparts/Default.aspx?mscssid=FC23CC6CD47045B787323CB7164142CE

[rsdofny]

Thanks a lot for your help