Hello and welcome to Bleepingcomputer.
As you can see from my signature below I have professional electronics repair experience.
Here is a warning for you and anyone who reads this thread: DO NOT ALLOW THE COOLING FANS TO SPIN IF USING COMPRESSED AIR OR CANNED AIR!!!
Here is why this can cause damage to your motherboard.
Fans can be powered by electrical magnetic fields to make the fan spin.
Because magnetic fields are created by having - and + forces influencing a ferrite core, the possibility exists that if the fan was spun by other forces such as air rather than electricity, the fan spinning through the magnetic - and + fields has a reverse effect of actually generating electricity, such as that of a wind driven turbine.
The faster the fan is spun by wind force, the more electrical current it can produce, that current is NOT filtered DC, it is unfiltered AC current!
It is also NOT REGULATED AC CURRENT
and this current is fed back into the motherboard bypassing any possible filtering or regulation, this current can damage voltage sensitive IC chips and circuits.
I can not determine what AC current levels were passed through your computers components, but if you need to witness an example of what current your computer might have been subject to, try this experiment:
Obtain a VOM multimeter, analog or digital is fine, set the meter to AC VOLTS in the meters lowest range, now hook the two probes from the meter up to a case fan's red and black wire, not the yellow or other colored wire, that one is for the motherboard to monitor the fan speed, so ignore that third wire.
Once you have the meter's probes attached to the red and black fan wires, blow compressed air at the fan so it spins from the force of the air, observe the meter's response as the fan spins faster and slower, you'd be shocked to see what current may have entered your motherboard, which is why damage to the motherboard and associated hardware is very possible!
Please anyone reading this post, when cleaning your computer, please use any tool or your finger to stop the fan from spinning, or disconnect it from the motherboard.
Also using too much air force inside a computer or using vacuum cleaners is NOT advised, this can cause motherboard jumpers to get sucked into vacuum cleaners, or blown off their pins by compressed air, you may not even know this took place, specially if the vacuum cleaner sucked a jumper off of its pins, the fact will be known when you power up the PC only to find things going wrong that didn't happen before the cleaning took place.
It really pisses you off, you clean the computer case out thinking things will be much better only to find a whole new problem has popped up, for anyone who has experienced this issue, you better be checking your motherboard manual for locations of jumpers and double check if any are missing that should be there.
Some jumpers are soldered wires, some are little black plastic coated metal objects that connect two pins together on the motherboard. Some are switches with a simple flip, one direction is logic 0 the other is logic 1, in other words, off or on.
I really hope my lecture helps someone in the future and in your particular case, you may have damaged your monitor if it was connected to the computer during this erratic voltage issue when you blew out the computer with compressed air from an air compressor, I do not recommend you ever try using that much air force again in the future.
Try your monitor on another computer and see if it works, if not you know your monitor has an internal component issue, probably something is burned or shorted out.
I recommend your trying the monitor on another computer and come back here and post the results, I am here to help you as best I can.
Edited by MrBruce1959, 22 July 2011 - 09:07 PM.