Computer wont boot up

i have a gateway 2.8ghz pentium d 2gb ram computer that will not boot up anymore. I was playing an online game when i recieved the blue screen of death. when i restart my computer it will power on but not boot up and the screen is blank. The main computer fan is also very loud but not making any bad noises and is very clean. the motherboard light is on. it does seem that the power supply fan is not working or atleast i can not hear / see it working. this is strange because my dvd readers have power and also my graphics card fan spins. i have taken all the cards out of my computer down to the bare bones and restarted...... still blank screen. also before it crashed my pc did make a noise periodically - sounded like a "click" almost like a cpu sounds when it powers down but it never did. my first guess is that this is a power supply issue so im going to get a volt meter to check it. anyone agree or have other suggestions?

 

I had exactly the same problem a few days ago, couldn't get it to boot no matter how many times I tried. Mine was clicking too.
Unplugged the tower, put it on the table and took the side off, it was full of clumps of dust.
I got a small brush and loosened all the dust carefully from the motherboard and all the cables then stuck a vacuum cleaner in there to suck it all up, being very careful not to touch anything.
Put it all back together and switched on and its been fine ever since.
Small bit of dust must have been shorting the board out somewhere.

 

ive tried other monitors same thing. there is no dust inside the machine because it is almost brand new. ive reset the mobo battery. ive taken all the cards and reset all the cords still same thing. i think now that is is a mother board issue and i took it to the repair shop. it will be fixed under warrenty. thanks for all your help. ill post again when i get the diagnostic report.