My son has my family's oldest gaming PC, it's an i7 4790 with a 1660 TI and 16GB DDR3. It wasn't booting the last couple of days. I had time to look at it so we disconnected everything and threw it on the table with some good light and connected it to power so I could see what it was doing.
It was clear his three case fans were all dying, one was completely dead. One was in poor condition and one was starting to make noise. I already had extra case fans brand new in box sitting in my house, but I assumed old fans weren't what was keeping it from booting.
We removed all three bad fans, and with the case wide open, both sides front and top removed, I blew it out a little bit with canned air. It wasn't that dirty, just a little bit of dust came out. I checked with my fingers to see that the ram seemed seated and that all the connections seemed okay, but I didn't disconnect and reconnect anything, I just touched it.
I turned on the PC with no case fans (only an old CPU cooler connected) and it booted up. So we installed the three new case fans, and tested it again. It booted up again. We put it all back together and connected all the peripherals and it's working absolutely flawlessly.
So I am asking a question, but I want you for context to know that I have repaired hundreds of PCs, maybe close to a thousand. I have never fixed a boot issue by replacing case fans. I have read that some 20+ year-old PCs maybe would have that issue, but from what I understand a 12-year-old PC should not have boot impacted by case fans. So here's my question: was this just a ghost in the system, or is this actually possibly a real thing?
TL:DR We fixed his computer with three new case fans and the tiniest bit of canned air. Help me make it make sense.
Nice strawman. The strategy of the incompetent.