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CPU Fan starts very late for some reason

Last response: in Components
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July 30, 2013 12:01:42 AM

Hi!
So when I boot my computer up, all the case fans start from the first second but it takes like 6 seconds for the CPU fan to start and then it goes on full throttle for like a bit to cool off the heat it didn't before.

Is this a big problem which can cause errors later and how can I fix it?
July 30, 2013 12:09:10 AM

Veske said:
Hi!
So when I boot my computer up, all the case fans start from the first second but it takes like 6 seconds for the CPU fan to start and then it goes on full throttle for like a bit to cool off the heat it didn't before.

Is this a big problem which can cause errors later and how can I fix it?

This is a pretty bad problem - you could probably start a fire with the amount of heat a CPU gives out when it starts. You could try reinserting the CPU fan cable into the header - it might be loose.
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July 30, 2013 12:31:24 AM

Allright I will try to insert it again soon but I am pretty sure it's as in as it can be. Might it be the fault of a mobo too?
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July 30, 2013 12:39:04 AM

Veske said:
Allright I will try to insert it again soon but I am pretty sure it's as in as it can be. Might it be the fault of a mobo too?

It could be but I doubt there'd be issues with a fan header (a CPU fan header, no less).
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July 30, 2013 12:46:26 AM


When a PC starts up the cpu shouldn't be hot at all, so I'd see no issue with the fan starting 6 seconds later. You could essentially run a fanless cpu even until you hit the windows login / welcome screen. I know I've done it multiple times because I've forgotten plenty to plug in the fan header only to wonder why my computer shutsdown a few minutes after I start a game ( :p  ).

You can go into BIOS on startup and check cpu temps.
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July 30, 2013 12:48:00 AM

biopolar said:

When a PC starts up the cpu shouldn't be hot at all, so I'd see no issue with the fan starting 6 seconds later. You could essentially run a fanless cpu even until you hit the windows login / welcome screen. I know I've done it multiple times because I've forgotten plenty to plug in the fan header only to wonder why my computer shutsdown a few minutes after I start a game ( :p  ).

You can go into BIOS on startup and check cpu temps.


Without cooling a CPU will easily get to its thermal limit the instant it starts. A heatsink helps, but not by much. I don't know how you can get to start a game without the CPU fan on before having smoke everywhere and explosions and fire and all that other crazy stuff your CPU does when it overheats.
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July 30, 2013 12:58:34 AM

It's just an issue with a certain model of the intel stock fan. I work at an IT distributor which assembles PCs and we have this kind of issue a lot. We have identified at least 3 different models of Intel stock fans and one of them exhibits this behaviour.

We narrowed it down to that particular fan needing more voltage to start spinning. If you had your case open you would see that the fan tries to spin up 2 times before going full speed. I assume that it will need 10V+ to start spinning, and I would guess that the board sends 5V, then 7V and lastly 12V, putting it on full speed.

No need to worry though, your system is fine and everything is in check. If you do not like the "startup acoustics" though you could always install a cheap aftermarket heatsink.
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July 30, 2013 1:00:06 AM

I will see to mobo updates when I get home then. Maybe it's some mobo fault that can be fixed with a simple flash.
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July 30, 2013 1:03:32 AM

IwinFTW said:
biopolar said:

When a PC starts up the cpu shouldn't be hot at all, so I'd see no issue with the fan starting 6 seconds later. You could essentially run a fanless cpu even until you hit the windows login / welcome screen. I know I've done it multiple times because I've forgotten plenty to plug in the fan header only to wonder why my computer shutsdown a few minutes after I start a game ( :p  ).

You can go into BIOS on startup and check cpu temps.


Without cooling a CPU will easily get to its thermal limit the instant it starts. A heatsink helps, but not by much. I don't know how you can get to start a game without the CPU fan on before having smoke everywhere and explosions and fire and all that other crazy stuff your CPU does when it overheats.



Eh, the advantages of four peripheral fans, I suppose.
Though it's easy with my hsf's design to simply touch the fins and hand test the temp on startup with the fan header removed and never is it hot, warm perhaps, but not hot.
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July 30, 2013 1:11:36 AM

Well in my case I have the tiny little stock heatsink that came with my haswell i5 so I don't think it will take the heat very well without cooling I guess?

Also an intresting quote i found:

It may even be a feature designed to blow the dust off , I've heard of some fan/heatsink connected to a bios controlled fan header actually starting up full force in reverse to do just that and then stop and run normally.
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July 30, 2013 1:19:57 AM

Please read what I wrote before you go and do all kinds of unnecessary things.
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July 30, 2013 1:29:15 AM

Thank you for the answer Warrgarbl! So many posts came up here that I did not see yours for some reason on the first read. I guess I will just buy another heatsink later on but for now it's ok.
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