Yes, I still smoke. But habits may change over time, when you decide to turn your domicile into a rental property as opposed to selling it. I had to call in a specialist who cleans vents and ducts -- about $500. You may get used to the color of your wall-paint as a smoker, and think the paint is still "good." Try rubbing a patch of wall with a mild cleanser -- you'll see. $1,000 or more for a paint job.
Since your computer itself is an "air filter," what's wrong with taking your cancer-sticks outside on the patio? After all, part of the cancer risk comes from "second-hand" smoke, which gets inhaled several times when no cigarettes, pipes or stogies are burning.
Does the delay of Windows Update make you nervous, impatient -- eager to light up? Wait for it outdoors, I say.
As for the "risk," cancer, if detected too late, is swift. The preponderantly bigger risk is COPD and heart-attack. a 3-month prescription of Spiriva may cost you the equivalent of two upper-tier motherboards.
It's my view that this "smoker's motherboard" problem might have been avoided. The links for cleaning, are instructive, but that's a lot of trouble. While smoke residue is "not good" for PCBs, I'd focus my attention on the gold PCI-E and RAM contacts. If you see anything else the electronics cleaning fluid might benefit, make it a "target of opportunity."