I have a BIOSTAR iDEQ 200P computer running Windows XP. The system fan won't operate. It will operate in another system. I measured the voltages on JCFAN1 and only measured 4.93v on the +12v pin. Is this normal or is this the reason the fan doesn't work?Could be a setting in the BIOS that tells it not to run until a CERTAIN temperature - or the mainboard connection could be faulty?Any other power issues cropping up, reboots etc?,............have you added any new devices that draw more power recently?..........How old is the power supply?
Your readings indicate a problem and a drop of just 1 VOLT will start problems ...see if you can swap out that power supply for a known good unit......

ftp://ftp.biostar-usa.com/manuals/IDEQ%20200P/IDEQ200Pmanual.pdfNo random reboots that I know of, although I haven't left it running long ENOUGH to finish booting. With the system fan not running, I didn't want to take a chance. No new devices have been added. You're right Karnac, there is another power connector. I measured the +12v pin on JSFAN1 and it measured 4.9v. I also tested the P1 plug, using a power supply tester. It tested good. I tried starting it up again and noticed the case fan wasn't working either! I'm going to try to boot it up using an external fan and see if I can get to the BIOS. I'll let you know what I find.By random reboots I meant in the past few weeks did you experience random boots or screen freezing up while you were doing any cpu INTENSIVE ACTIVITES.....