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.
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I’ve built a lot of computers in my lifetime and my only guess when reading your post was that somehow one of them was causing a short and that short was somehow preventing the system from successfully posting, but I’m not sure how that would work exactly.
My level of technical knowledge ends about there. I can troubleshoot and swap hardware all day, but idk how a case fan would cause a system not to boot specifically.
Unless… Was one of the case fans running from the CPU header for some reason? Maybe the board thought the CPU fan was cooked and it was preventing a boot for safety? I’ve never seen anything like that safety speaking, but I could believe it exists.
Maybe the board thought the CPU fan was cooked and it was preventing a boot for safety? I’ve never seen anything like that safety speaking, but I could believe it exists.
I’ve owned and worked on computers that have that as a safety feature. If the CPU fan wasn’t connected or wasn’t working, they wouldn’t boot. They would usually have a beep code to let you know, but that’s assuming that there’s a motherboard speaker and it’s working.
A shorted fan would probably trigger it, as they would usually use the third cable on the fan connector to measure the rpm and check that the fan was spinning 👍
Man I used to check if systems would post without a cpu cooler installed at all back in the day. I wouldn’t run it for more than a few seconds but just long enough to make sure it was posting.
Had a buddy burn his finger pretty good because he wanted to know how hot a cpu would get without a cooler lol. Turns out they get hot enough to burn humans within a couple seconds lol
How old is that power supply? I’ve seen several that just the act of it being unplugged for 5 minutes allows it to boot again.
The theory being a capacitor or such needed a chance to calm down a bit somewhere, and something in the power supply or mainboard would proceed until power was back to normal.
Especially common if there’s brownouts or surges.
I know this post was from a few weeks ago. The PC is still working perfectly with its old PSU. My guess was the one case fan that was completely seized was drawing too much power or causing a short. I may still replace his PSU since I already have a good replacement, but I might wait until I have a GPU upgrade for him and just build a new rig for him. I pass my video cards down to my kids as I upgrade.
People in the comments had mentioned I didn’t really explain what it was doing. It would spin up the fans for about two seconds and then shut down, it wasn’t posting. That motherboard doesn’t have a code display, it will give beep codes for some errors but it wasn’t beeping, it just powered down. Whatever, it’s working well again, and as old as it is, it runs the games he plays very well at 1080p/60fps which is all his monitor supports so I’m not in a hurry to build him a new rig just yet.
