Question HP Z400 - How to remove rear chassis fan and get round "513-Rear Chassis Fan Not Detected" error ?

Jun 9, 2023
Hi - my first post here after months of tech support lurking!

I'm trying to strip a HP Z400 down to just PSU, Motherboard, Hard Drive.

I've sorted the errors caused by removing Firewire '913-Front 1394 Not Connected' and Audio '917-Front Audio Not Connected' through BIOS changes and USB '918-Front USB Not Connected' through a hardware jumper pin - but the '513-Rear Chassis fan not detected' error I'm getting when I remove that part has me stumped.

I've seen people post about connecting the 'sense' pin of the CPU fan connector to the same pin on the rear chassis fan connector and it looks like that would be pin 3 (green wire) on both the 5 pin CPU fan and the 4 pin chassis fan connectors.

There's posts here and here related to this and on my machine both those cables have what I believe is 1: GND (Black) 2: +12V (Yellow) 3: Sense/RPM Feedback (Green) 4: PWM Control (Blue) (with the 5 pin connector doubling up on the GND for the CPU fan).

Before I start hacking into molex connectors - is there anyone here that can offer any advice on whether the solutions listed above work or if there's any other way of dealing with this?

Just to be clear - I'm looking to completely remove the rear chassis fan - not replace it.


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"but the '513-Rear Chassis fan not detected' error I'm getting when I remove that part has me stumped.".

Is that error getting in the way of something to where the error message cannot be simply ignored?

I would be leery about anything that would fool a system into believing that a fan is present when the fan is not present.

Understand that you require a stripped down system but would be remiss if I did not ask about the overall requirements.

You may need some code to make the error message go away or be ignored.

More information needed.
Jun 9, 2023
Hi - thanks for the reply.

I would prefer to find a way of removing the error message than just ignoring it - but there isn't a reason why I couldn't just ignore it.

Initially, my concern was that if I'm running this headless and connecting to it via Remote Desktop - if I ever needed to reboot, I wouldn't be able to connect to it remotely until it had got past that error message and fully rebooted...

...but in writing this reply I've realised I probably could just connect the keyboard, hit F1 and get on with it. Not perfect but a pretty simple workaround.

Do understand that removing fans is not to be taken lightly and I'm definitely going to keep an eye on the impact that has on temperatures - but given that it seems the error message is basically just a sensor pin that's reading as not connected - then I'd still prefer to try and deal with that - even if I am tricking it into thinking it is connected.
Jun 9, 2023
Just in case anyone else ever needs to deal with this...

Running a jumper cable from pin 3 (green wire) on the 5 pin CPU fan to the 4 pin chassis fan gets rid of the '513-Rear Chassis fan not detected' startup error.

Removing the rear-chassis fan did cause an increase in CPU heat that did cause it to shut down and reboot overnight (I'm assuming that's what caused it as it has been hot here) but I'm hoping that heat increase will be more sufficiently offset once I pull the PSU, CPU and HDD out and run it 'open case' style.