by 'blow' I guess you mean
Canned air ( electrical contact cleaner) like dividebyzero said?
"Canned air", and, "electrical contact cleaner" are two entirely different things ."Electrical contact is a chloroflourocarbon FLUID, and the "air" is well, just that, a can full of air, (albeit compressed).
And yes, that's what they meant by "blow"!
I have a 5 HP air compressor in my living room. Which BTW, I blow the dlckens out of just about everything in sight, tires, spray guns, DA sanders, and last but not least, the insides of computers.. But, by all accounts, I am quite eccentric.
I had the same issues with Dell awhile back, I bought a Pentium 4 Machine back in the day because it was on sale thinking that I could upgrade and work on it later (This has been about 9 years ago now) and to my shock, the AGP slot was removed/Never put on...Yea they said I could add stuff to the slots...But I was stuck with a PCI-Bus Graphics card lol.
Yeah well, it was at least that embarrassing for me. I treid to stuff the PCI-E video card in the PCI slot, and it actually took me a couple of minutes to figure out why the hell the VGA monitor socket was pointing toward the inside the machine.
On a lighter note. Those were the days of Bestec OEM PSUs, (usually no more than 300 watts, (on a good day, if that). And video cards sucked way more volts per FLOP, or whatever you want to call that. "Amps per FLOP", maybe? So, by sacking the add in graphics card socket, manufacturers circumvented an almost certain warranty claim on their crappy PSUs.