Get an error on boot "Alert - Rear Fan Failure". Any ideas as to what the cuase is?
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.
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?
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.
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?
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.
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The USFF has a fan under the hard drive.
USFF Hard Drive Fan Hk120