As I understand it, a quick scan (such as McAfee) is checking the likeliest places for a virus to infect a computer, whereas a full scan checks the whole computer, everything.
Does a Quick Scan then cover, say, 90% of the places a virus could lurk in on one’s computer? (A full scan tends to overheat the CPU, so I can’t do it.) How probable is it that a virus could lurk somewhere on a computer that can only be found by full scan but not quick scan?
I don’t think it’s possible to put a number on that. A quick scan is designed to check the places where experience says that a virus is most likely to hide. So it’s the most effective in terms of time, etc.
If you would like the peace of mind of doing a full scan, at least some programs will let you pause the scan for a while and then resume it. That might help out your CPU. You may also want to open the computer (if a desktop) and clear out the dust.
That isn’t right – something in your machine is bad. Check that out, before it gets worse. (Could be as simple as dust accumulation, as bootb suggested. But it could be more serious.)
I just opened this thread. Totally expected it to be about Covid.
Think of it as an arms race. The quick scanners hit the usual spots (boot sector, OS folders, etc). The hackers find a new spot. The quick scanners add that spot to the “usual spots” list. The hackers find a new spot. The quick scanners add that spot to the “usual spots” list. Ad infinitum.
A full scan hits all the spots - including ones that have had never had a virus.
Follow-up question: Why does a Quick Scan sometimes drop down in percentage of files scanned? It will say something like “57% progress scanned” but then go down to “42% scanned”, how does that work?