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JB

Jeremy Bentham

2 Posts

1653084

March 17th, 2009 15:00

Optiplex 755 Rear Fan Failure

Get an error on boot "Alert - Rear Fan Failure".  Any ideas as to what the cuase is?

shesagordie

10 Elder

 • 

46K Posts

March 17th, 2009 16:00

Get an error on boot "Alert - Rear Fan Failure".  Any ideas as to what the cuase is?

 

Jeremy Bentham

Have you replaced the fan recently?

Maybe power supply is not properly connected to the motherboard, fan has a dust buildup that it stops rotating properly, fan burnt out.

Bev.

Jeremy Bentham

2 Posts

March 17th, 2009 21:00

I don't have a fan on this machine since it is the smaller form factor.  The only fan is the fan on the power supply.  Does the power supply need to be replaced?

shesagordie

10 Elder

 • 

46K Posts

March 18th, 2009 14:00

Jeremy Bentham

The small form factor system has a hard drive fan at the back of the case, see HERE <ADMIN NOTE: Broken link has been removed from this post by Dell>

Bev.

charlescoke

2 Posts

January 30th, 2012 13:00

Replace the fan. It is cheap and easy.

 

charlescoke

2 Posts

January 30th, 2012 13:00

My 755 has 3 fans. 1 on front, 1 at he power supply in back and 1 on the hard drive. Take the side cover off and you can see 2 of the fans. Run the diagnostics and see what it tells you. The hard part is finding a supplier.

speedstep

9 Legend

 • 

47K Posts

January 30th, 2012 18:00

Replacing a Hard Drive Fan

  1. Follow the procedures in <ADMIN NOTE: Broken link has been removed / replaced from this post by Dell>


  2. Remove the computer cover (see Removing the Computer Cover). <ADMIN NOTE: Broken link has been removed from this post by Dell> 

  3. Remove the hard drive (see <ADMIN NOTE: Broken link has been removed / replaced from this post by Dell>


  4. Turn the hard drive upside down, so that the hard drive fan is visible in the bottom of the drive bracket. 

  5. To remove the hard drive fan: 

    1. Lift the release tab on the back panel of the fan. 

    1. Rotate the fan in the opposite direction from that indicated by the arrow on the back panel of the fan. 

    2. Lift to remove the fan and its back panel from the hard drive bracket. 

Replacing a Hard Drive Fan

  1. Follow the instructions in <ADMIN NOTE: Broken link has been removed / replaced from this post by Dell>


  2. Remove the hard drive (see Hard Drive).

  3. Remove the hard drive fan:

    1. Remove the screw that secures the fan release tab to the hard drive bracket.

    1. Press down on the fan release tab, and then slide the fan towards the front of the computer so that its side tabs are free of the corresponding slots in the hard drive bracket.

    2. Lift to remove the fan from the hard drive bracket.

    3. Unplug the fan.

eMicros

5 Posts

February 10th, 2012 02:00

Sorry to piggy back on this, I'll create a new thread if required.

 

I have the same issue with an Optiplex 755, but it was brought about by upgrading it.

It had XP and a P4 in it, and I wanted to upgrade it to WIn7.

So, I installed a spare dual core CPU I had and installed Win7 on it.

Firstly it complained that the CPU was unsupported, during bootup, although it worked and

Win7 recognised it just fine. But to overcome the annoying message, I upgraded the BIOS to the latest

available on Dell's download site. Now I get an even more annnoying message, with it telling me

"Alert! Rear fan failure ...". But there is no rear fan (hard drive fan) on this , its the ultra small form factor.

The plastic hard drive tray does not have the fan on it, nor has it ever had the fan on it.

But now I get this error every time I restart and I have to press F1 to boot. I need this PC to auto on after a power cut,

but it won't as it wants F1 pressed. I cannot find any way to disable this error. I don't have a fan! It worked fine under old BIOS.

Grrr ... any ideas chaps?

DELL-John C

5 Practitioner

 • 

353 Posts

February 10th, 2012 03:00

Hi eMicros,

In this case, I have to say that the updated BIOS you have installed is working as designed. If the Optiplex 755 USFF you have doesn't have a hard drive fan, then you will get this error appearing on screen and there is no option in the BIOS to disable this. Please see the manual for confirmation that this system should have a hard drive fan:  <ADMIN NOTE: Broken link has been removed / replaced from this post by Dell>

To resolve this, you'd have to install the hard drive fan - Dell part number HK253.

speedstep

9 Legend

 • 

47K Posts

February 10th, 2012 06:00

The USFF has a fan under the hard drive.

USFF Hard Drive Fan Hk120


Replacing a Hard Drive Fan

  1. Follow the instructions in Before You Begin.

  2. Remove the hard drive (see Hard Drive).

  3. Remove the hard drive fan:

    1. Remove the screw that secures the fan release tab to the hard drive bracket.

    1. Press down on the fan release tab, and then slide the fan towards the front of the computer so that its side tabs are free of the corresponding slots in the hard drive bracket.

    2. Lift to remove the fan from the hard drive bracket.

    3. Unplug the fan.

speedstep

9 Legend

 • 

47K Posts

February 10th, 2012 09:00

Keep in Mind that the Models Vary based on the Case.

HK120

The USFF Fan is HK120

eMicros

5 Posts

February 10th, 2012 09:00

Thanks for this. I'm aware that conventional wisdom and info found in service manuals insists tht there is a fan on the hard drive caddie, but honestly, on mine there is not and never has been. No fan, no power cable, just a plastic tray to clip the hdd in. That's the lot! And on the original bios it didn't care. But on the latest bios which enables it to recognize my CPU, it is not at all happy about the fan that I've never had and it never complained about on the old bios :( If buying a fan is not too expensive, sounds like a reasonable resolution

eMicros

5 Posts

February 10th, 2012 13:00

Ok, so it turns out that i have the SFF, not the USFF!

DELL-John C

5 Practitioner

 • 

353 Posts

February 13th, 2012 01:00

Hi eMicros,

I've just double-checked and the Optiplex 755 SFF should also have a hard drive fan installed as shown by

 - also, can you confirm that your hard drive caddy is like the picture below?

It may have been the case that in earlier versions of the BIOS that the hard drive fan status was not polled by the BIOS and so didn't give you the warning, however with your latest BIOS, you will require a replacement hard drive fan to resolve the problem. The part number for the SFF hard drive fan is TJ160.

speedstep

9 Legend

 • 

47K Posts

February 13th, 2012 07:00

Genuine Dell NY290 Hard Drive Blower Fan and NH645 Hard Drive Caddy, For The Optiplex 740, 745, 755, 760 Small Form Factor (SFF) Systems, Compatible Part Numbers: TJ160, NJ793

Genuine dell ny290 hard drive blower fan and nh645 hard ...

Genuine Dell NY290 PC Blower MCH Fan For Optiplex 740 745 Hard Drive Bracket Part Numbers TJ160 / NH645  

eMicros

5 Posts

February 13th, 2012 08:00

Hi, this is exactly what mine looks like! Black tray with no fan :(

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