511 CPU FAN not detected, but fan is blowing at full speed.

[RensMasselink]

Hi all,

Hope you all can help with this. When the workstation (HP Z420) boots up it gives an error message 511: CPU FAN not detected. The fan is turning at full speed and seems to work ok.  CPU temperatures are around 40 degrees when idle, so it seems the fan is doing its job.

It is, however, a bit annoying that it is blasting at full speed the whole time so i wanted to fix it. Unfortunately i found out now that the warranty has expired last October (2016), even though the problem is already ocurring for more than a year.

I have tried to update the bios to the latest version, reset the bios using the cmos reset button on the motherboard and i have reseated the cpu fan and the cpu fan cable. All to no avail.

Are there any other options i can look at?

Thank you in advance for your help.

Kind regards,

Rens

[mdklassen]

Your motherboard may have multiple connection-points for fans:

* CPU fan

* chassis fan #1

* chassis fan #2

Check that the wires from the actual CPU fan are connected to the "CPU fan" connection point that is labelled on the motherboard.

In the BIOS Setup, there are options to "ignore" any monitoring of the connection-points that are *NOT* connected to any fan. Check that the options are correctly set to match the connections that you actually have.

Or, totally different, the heat-sensor inside the actual CPU fan might have failed, always returning "this porridge is too hot", and so that motherboard responds by [noisily] running the fan at 100%, in an attempt to cool the porridge cown.

Replace the fan.

[RensMasselink]

Thank you for the reply.
The cpu fan is connected to the correct connection point, so it should neither be a question of connecting it somewhere else, nor ignoring the error message. With ignoring the error message the problem does not go away.

All core temperatures are displayed correctly, so I also don't think the sensors are broken, right?

Any other options that come to mind? Thanks

[mdklassen]

> All core temperatures are displayed correctly, so I also don't think the sensors are broken, right?

Agree.  However, it's still possible that the "speed-controls" inside the fan are not responding to "slow down" commands.

Replacing the fan is the only way to confirm this guess.

> Any other options that come to mind?

Check BIOS SETUP.  On some systems, it's possible to configure the fan to "always 100%" speed.

[gabornico]

the BIOS gets no signal from the fan's rpm sensor (pin 3), that's the reason why the CPU fan runs at full speed.

Solution: replace the fan.

It's not possible to disable this error message in BIOS setup.

[mdklassen]

> It's not possible to disable this error message in BIOS setup.

Changing the setting for the fan to "ignore" will disable the speed-monitoring (but that's not the problem, in this case).

To repeat what I wrote: replace the fan.

[SDH]

I'm with mdklassen on this..... and where do you get such a replacement fan, the exact right HP one?

Go to eBay and buy a replacement heatsink/fan for what you currently have.  You can harvest the fan from that.  I saw some for $17.00 USD shipping included today.  These fans very rarely go bad.  I buy used HP fans often off eBay, and have never bough a bad one.

The way the fan is mounted on the heatsink you cannot see its label.... the label is facing the heatsink fins.  I'm guessing you could remove the heatsink and clean off the processor and put on new thermal compound (Noctua is my favorite, for years now).  When you are doing that you can take the fan off and copy down the part number  and the little hyphenated modifier alphanumeric if present and even search for the fan by itself to save a couple of dollars.

You can get the heatsink number off the label on its side...... also note the type of white fan plug end you have..... usually 5 holes with a ground jumper from pin 1 to 5.  Go look on eBay under "Z420 heatsink"

[mdklassen]

See: http://h20566.www2.hp.com/portal/site/hpsc/template.PAGE/public/psi/manualsResults/?sp4ts.oid=522503...

for "HP Z220 SFF, Z220 CMT, Z420, Z620, and Z820 Workstations Maintenance and Service Guide "

or: http://h20566.www2.hp.com/hpsc/doc/public/display?sp4ts.oid=5225033&docLocale=en_US&docId=emr_na-c04...

You should be able to get the HP part-number of the fan.

Then, use:  http://PartSurfer.hp.com

to order a replacement fan.

[SDH]

I wish you could, but you can't.

Use Google to search for "Z620 spare parts" and you'll find the HP spare parts page for the Z620 near or at the top, but it doesn't get into that level of detail.  If you call HP you might track one down, but have fun doing that, and don't do it from a pay phone.

HP sometimes uses the same fan for different purposes, but this one in the images has the 5-hole white plug with ground jumper from 1 to 5 (which generally is how HP tells the motherboard a "Performance" heatsink/fan is attached).  That is what the little hyphenated alphanumeric on the label is all about...

Most don't know that.... now you do, but even the sellers don't know that so there usually is no reference to that in eBay ads (but you can see it if they give you a good enough picture).  There is a good place in China (where most of the parts are made) that does reference the alphanumeric, but their parts are new and expensive.  I go eBay.

[42OZ]

Were you able to fix this problem?

I have the same message but the error # is 513.

My Z420 is liquid cooled, could that have anything to do with my error message?