Fan runs super fast. HP Compaq dc5100 SFF

[externmed]

The last several days HP Compaq dc5100 SFF--  fan(s) have been running apparently superfast fan speed.

Was full of dust (to the point of blocking the intake on the front fan) 

Used a AIR CAN blow dust out with cover open.  We also had a brief power blip in the last few days--caused a shut down.  And we updated some business software.  Has been rebooted.

We have 3 other of same model which are OK

Thanks for any help

[Paul_Tikkanen]

Hi:

Did you really get the dust out of the heat sink fins?  They are very narrow and dust gets caught in those. Make absolutely sure you got all the dust out from in between those heat sink fins.

Paul

[externmed]

Hi,

Thanks for the thought.  I'll check it out again.

Thanks much.

[cdgraves · Accepted solution]

The dc5100 SFF is notorious for bad capacitors on the motherboard.  I had one where the fan ran at top speed all the time.  There was a swollen capacitor located at the end of PCI slot 1.  I believe it is C469.  It is a 1000uF 6.3volt cap.  I replaced the capacitor and that fixed the problem.  Keeping the computer cool will lengthen the life of the capacitors.  It is wise to periodically remove the dust so cooling air will flow.  How ever, once a capacitor goes bad, the only fix is to replace it.  A blown capacitor will be swollen. The normally flat top will be curved upward and possibly leaking a brown crusty material.

[blitz_8255]

That was the ticket!! Changed the cap and all is well! Thanks for posting the fix. I've got a few of these that I can use now.

[mookseberg]

Hi, I do have the same problem: a CPU fan running very fast.

I have another HP Compaq: I have the minitower version of the HP5100.

Does it have the same motherboard? and if so, can you tell me exactly where I can find this cap?

I have been looking for a swollen cap, but I can't find one. It's possible that the cap is broken, though it is not swollen.

Please your reply.

Thanks, Jan, The Netherlands

[Magefyre]

Looks like that's it, all right. Cap at the end of PCI1 is swollen and in the BIOS under thermal it did not show a fan idle speed (can't read it?)