HELP PLZ new comp won't start up!!!

[Ncab]

Hey, I have just assembled a new computer and I have some problems turning it on. I suspect the startup has something to do with the powersupply or motherboard. Whenever I try and see if it shows any sign of turning on I have to have nothing plugged-in in the I/O place the only thing I can actually plug-in is the power supply and then it usually turns on but only the fans and 2 of my IDE divices. The front panel of my case also shows that the power isnt on but the HDD is. If you have any idea of what could be wrong please respond soon!

 

[ovvn.you]

it powers on, so it doesnt sound like the powersupply or the motherboard is at fault, bios??

 

[Jono91]

Is the 4 pin power connector plugged in to the motherboard, that happened to me, everything else worked but the monitor wouldn't turn on. Also with the front panel Power LED, you might have plugged it in on the motherboard the wrong way around or something. also if you have on-board video, plug your monitor into that instead of a video card.