Can a noisy cpu fan stop computer from booting?

[riddellcomp]

I have a computer that wont boot and im suspecting it could be the cpu fan thats causing the problem. I was installing a new drive on the computer and having troubles so was rebooting a lot. Then the cpu fan started to make a grinding noise like worn bearings and the computer stopped booting at about the same time. I cant get anything on the screen what so ever but have tested the drive in another machine and its okay. I assumed that a faulty fan could stop a computer if the cpu gets too hot but that didn't happen in this case. The fan was still spinning and when it first happened the BIOS showed the cpu temp at around 32C.
Can the Bios detect a fan that spins slower than it should and stop the computer from booting?

[Gollo]

Yes it can (if it's plugged into the mobo and the bios is configured to do so). Try swapping the cooler and see if it boots then.

[joelen]

Short answer, yes.

System may have overheated due to bad fan, cuasing it not to post. Hopefully this is just a temporary, 'its still too hot to boot' situation, and not a cooked cpu. I would recomend leaving it for an hour, trying again. If it does post, swap the fan, and you should be back in business.

Joe

[cisco2]

I suppose a short could cause odd problems that might cause your PC to not boot.

I wouldn't normally expect that to be the cause of booting problems so severe that you get nothing on the screen. If it was overheated it might not try to boot until after it has cooled but at some point it should boot at least far enough to get into the BIOS.

Certainly faulty fans that might cause overheating should be repaired but generally speaking a noisy fan has to spin to make noise so you've got air flow and the noise is more of a warning that the fan is about to go.

I would start simplifying. Remove or disconnect anything unnecessary. CD/DVD Drives, Modem/NIC, sound cards. Pretty much all you need to boot is a floppy drive, CPU, RAM, video, and keyboard. Disconnect everything else and see if it will boot. If not then you need to do some low level fault isolation, generally that means inspecting cables and verifying connections and swapping out components like video card, CPU, RAM, and PSU.

Try another video card first, then try the PSU. If it's not one of those then you're probably looking at replacing one or all three of CPU, RAM, and motherboard. Try reseating the CPU and RAM at this point, be cautious of static discharge.

If it boots after simplifying, start adding cards/devices one at a time to see if you can identify whatever is/was causing the problem.

[riddellcomp]

I know that its certainly not an overheating problem as the fan still spins okay its just too nosiy. I disconnected it and at some point the computer stopped botting so am not 100 sure if it was due to the fan or not.

I will try your advice cisco2 and see how i go with it. everything was working fine until the fan started making a noise so Im suspecting the fan is the cause.

[Stalemate]

I know that its certainly not an overheating problem as the fan still spins okay its just too nosiy. I disconnected it and at some point the computer stopped botting so am not 100 sure if it was due to the fan or not...

You disconnected the fan's power, or its sensor?

Fan off = overheating within seconds.

[gazzak]

Stop messing about with the fan and throw it in the bin. Now!!

For a couple of quid, (or bucks), you have a new fan in place and no more problem, game over!

(have had fans cause a power loss before due to faults)

[Atodini]

Riddellcomp,

From your last post I interpret that you either powered up with the fan disconnected or disconnected with the power on. If you powered up with the fan / heatsink assembly removed then the cpu will be toast!!

Is the cpu an AMD (Athlon/Duron) or Intel (Pentium 3/4 or Celeron)?

If AMD, I would guess that the cpu is toasted. If Intel Celeron you might have got away with it (as long as you only disconnected the fan for a very short time. on its own, without the fan running, the heatsink will only contain the temperature rise of the cpu core for a very short time.... with an AMD probably less than 2 seconds! The temperature rise to burn out cycle is so fast it will not be picked up, by the motherboard temperature sensor. Although Intels have overtemperature protection, without the fan running the rise may well be too fast for this to protect the cpu.

In either case powering up with the fan removed will burn out the processor = no boot!

John

John

[riddellcomp]

Riddellcomp,

From your last post I interpret that you either powered up with the fan disconnected or disconnected with the power on. If you powered up with the fan / heatsink assembly removed then the cpu will be toast!!

Is the cpu an AMD (Athlon/Duron) or Intel (Pentium 3/4 or Celeron)?

If AMD, I would guess that the cpu is toasted. If Intel Celeron you might have got away with it (as long as you only disconnected the fan for a very short time. on its own, without the fan running, the heatsink will only contain the temperature rise of the cpu core for a very short time.... with an AMD probably less than 2 seconds! The temperature rise to burn out cycle is so fast it will not be picked up, by the motherboard temperature sensor. Although Intels have overtemperature protection, without the fan running the rise may well be too fast for this to protect the cpu.

In either case powering up with the fan removed will burn out the processor = no boot!

John

John

Its a 450mhz P2 in one of those long slot 1 cartridges with the full size heatsink. I wanted to be sure it was the cpu fan that was causing the noise so I shut down the comp, disconnected the fan and rebooted. Then on a subsequent boot (Although still without the fan) it wouldn't fire at all. The hdd light flashes once briefly and thats as far as it gets. How can I be sure?
I thought the large hdd would have handled the heat for such a brief period.

[Atodini]

Hi riddellcomp.

The slot type pentium II's did not have the thermal protection that the socket ones have so my guess is that the cpu has died.

The next course for you is to try a known good replacement processor with fan connected.

The symptom, only a flash from the ide LED and (I presume) a brief flash of the LED's on the keyboard would tend to confirm this.

If the replacement cpu is not a PII 450, you'll need to reset the jumpers on the board for the correct fsb & voltage settings before powering up. These are often printed on the board somewhwere, if not you'll need the board manual.

Sorry I can't be more positive....

John

[riddellcomp]

Okay this is going to surprise some of you as it did me and I swear Im not making this up.

I went to my local pc store (Which luckily I get along with the owner well enough) as he gave me two slot 1 p3 450mhz cpu's to try out in the mobo. I went home and tried them both but neither of them managed to get the computer to boot. In fact on the mobo all of the leds were red. I know that when I was trying to boot up with the original cpu without a fan two of the leds were green. I'm not sure what the exact code means as the msi forum is down and I cant find anything on it in the mobo pdf doc I have.

So I decided to give the orignal cpu another go with the fan connected up from one of the borrowed cpu's.

Guess what it worked.

I got an error message about "Abnormal hardware setting" which related to the fact that the fan only had positive and negative wires and no fan speed sensor. (As the fan rpm was shown as zero.)

Anyway it works fine now I just need to get a different fan that has the rpm sensor also.

[Stalemate]

Great news.

Those CPUs were much toughr than today's higher performance versions.

Why, it was about 14 months ago that I sold my last P2 for 400$ (no monitor either).

I don't recall the exact specs, and I'm too lazy to look them up, but I think the P3 450MHz operated on a different FSB than the P2 at the same speed. That might explain why it didn't "take".

[3FS]

That is great news, you got very lucky. In the future I would NEVER boot a computer without a CPU fan hooked up though, the results could be tragic!! If you want to confirm it is the CPU fan, just put your ear close enough to that part of the case to confirm it. Most times, a noisy fan is not spinning at full speed, so you can visually see it turning slow, which would confirm your suspicions as well.

[riddellcomp]

That is great news, you got very lucky. In the future I would NEVER boot a computer without a CPU fan hooked up though, the results could be tragic!! If you want to confirm it is the CPU fan, just put your ear close enough to that part of the case to confirm it. Most times, a noisy fan is not spinning at full speed, so you can visually see it turning slow, which would confirm your suspicions as well.

Thanks 3FS point taken. I did see it spinning slowly and just thought I would disconnect it to make sure. I will know for next time though.

Thanks again to everyone.