getting cockroaches out of computer

Solution
Assuming they are alive.

First, turn the computer off, move it to a closed space and spray into the space with bug spray (not directly onto the computer). Give it around half an hour to do its thing and then let the area vent (make sure not to breath it in). Take your PC to an outside area with a bin to dispose of the roaches. Depending on how bad it is, you might need some gloves and a stick to dislodge all the roaches, and you will have to remove all the components to make sure there are no dead roaches hiding behind the motherboard and other such crevasses. Once you have all the roaches out, you'll want to hit everything with canned air duster.

Once you're done cleaning it, you'll want to spray the area around where the computer...
Assuming they are alive.

First, turn the computer off, move it to a closed space and spray into the space with bug spray (not directly onto the computer). Give it around half an hour to do its thing and then let the area vent (make sure not to breath it in). Take your PC to an outside area with a bin to dispose of the roaches. Depending on how bad it is, you might need some gloves and a stick to dislodge all the roaches, and you will have to remove all the components to make sure there are no dead roaches hiding behind the motherboard and other such crevasses. Once you have all the roaches out, you'll want to hit everything with canned air duster.

Once you're done cleaning it, you'll want to spray the area around where the computer normally is, repeating every so often (there should be instructions on how often to surface spray on your bug spray), maybe consider moving it to a higher location away from any potential food sources.
 
Solution
I would suggest placing newspapers on a flat surface. Then remove one of the sides of the desktop case. Then spray your roach spray on the newspaper, and then place the open side on the newspaper.

Then after a few hours thoroughly clean out the desktop and reassemble.
 
Getting them out? it is quite easy.
You do not really need chemical to force the out.
Take your PC to outdoor like in your garden.
Some will crawl to your hand, so do not freak out!
Open the PC.
Just blow them away with a blower.
They will come out. Trust me.
After that, clean the PC thoroughly incl. using alcohol (90%) or PCB cleaner spray.

That is not the important part.
It is way more important to keep them away from your PC.
Like:
- cleaning it more often
- put the pc away from moisture incl. paper

Most important:
Take care of your pest problem in the house!