HP Z400 Fan Noise Reduction

[Wesso]

Hello, as the title suggests, I have a HP Z400 (revision 2, with 6 RAM slots) and I'm having some troubles with the fan noise. 

I got this machine second hand but I do believe the fans used are all original parts. Based on what I've read, the HP Z400 fans are just generally quite loud. 

I've been thinking of moving the parts to a Corsair case that has sound proofing to reduce the noise and at the same time I was thinking of upgrading the fans to some quieter ones but from a quick scan on the forum it seems like HP has their own cooling methods so aftermarket fans will cause bad results. 

Two main points struck me to post on here, and I hope someone out there has figured this out at some point and is able to provide some detailed instructions on how I can get my Z400 to run quieter.

1. I understand the motherboard can somehow detect whether the fans are originals or not (perhaps identified via RPM as one post suggested). 
2. The CPU fan socket is a 5-pin

Given the above two points, can anyone assist with my requirement (reducing fan noise).

Thank you.

[DGroves]

first of all moving the motherboard to a new case will most likely be counterproductive from a noise/cooling perspective

to move it you will need a new power supply, a power cable adapter as the z400 supply/motherboard is not ATX compatable

https://www.moddiy.com/products/ATX-to-HP-Z400-24%252dPin-Non%252dStandard-ATX-Pinout-Main-Power-Ada...

the z400 cpu cooling connector is 5 pins and is simply a standard PWM 4 pin connector with a HP added 5th pin that allows the bios to determine if a high power heatsink is installed by running a jumper between pin's 1 and 5

HP fans are easy to detect as the label on the fan will carry the hp part number of that fan

it's not advisable to replace fans with non hp ones as the fans hp uses are custom units tuned to the case to provide proper airflow. you can replace one case fan with a 3rd party one if you match the rpm range of the existing fan by using a strobe type meter on the existing hp fan or place a tempture probe from a multimeter inside the case and compare temps between the old fan and the new one

[SDH]

Another tip.... make sure in BIOS that the fans are set to the lowest speed possible.  Sometimes the prior owner has boosted up the  RPMs there and you might not know about that.  I bet virtually all of us keep the BIOS setting to slowest possible, and a few might boost fan speed in BIOS only during processor intensive project.

[Wesso]

Thanks for the heads up about the power supply and the non conventional connector from PSU to MB.

Given your replies, then do you think this may work if I used he HP Z400 original PSU (one I currently have in my HP case) in the new case?

And if I leave the CPU cooler as is but replace the front and rear fans, will this cause any issues?

Essentially what I plan to do is get the Fractal design Define R5 which has good sound proof padding.
Move the HP Z400 motherboard and PSU to that case.
Keep Z400 stock cooling heatsink/fan.
Connect Noctua NF-A14 PWM (4-pin, 2000RPM) as rear case fan.
Use the two 140mm (3-pin) fans that came with the Fractal design case as front fans (either connect them both onto a fan slot on the motherboard, use Y splitter on it which is connected to only one fan slot on motherboard).

I understand the front fans will be at 100% due to them being 3-pins but I think the noise won’t be as bad as it is now anyways given all the sound proofing.

Thoughts?

[SDH · Accepted solution]

I have posted in this forum about use of Noctua PWM fans.... read up on that.

I settled on use of the very high quality HP original fans and have added in the Noctua 4-wire PWM fan speed reducers.

For the Z400 use a 4-wire Low Noise Adapter (LNA) on the front fan and one on the rear fan.... these can be found individually as the NA-RC7 or as a pack of 3 as the NA-SRC7.  There also is a 4-wire higher ohm ULNA (ultra low noise adapter), the NA-RC6.  The 4th wire allows PWM control from the HP motherboard back to the fan's motor.  For my Z600 builds I use a 4 wire ULNA on the small too-fast chipset cooler fan, which are somewhat hard to find.  For some of the motherboard 4-pin headers you may need to carefully shave down a ridge on the female end of the adapter.

This approach lets the motherboard's PWM control system still work in concert with the HP fans, but having the resistor in the 12VDC line drops the voltage from 12 down to maybe 8V and 6V for the LNA and the ULNA respectively.

If you use Noctua PWM fans they start slow and quiet at 12VDC, but run way too slow when the baseline HP PWM control is applied to them at 12V.

You can always make fans run so slow that they are worthless.  HP put a lot of work into engineering as much quiet as they could for general high end workstation use here..... but for those who won't be hammering their Z400s with jet engine design there is some room for slowing the original fans down my way.  Don't overdo it.  You can monitor some of the temps with CPUID.com's free HWMonitor (which I have used for years now).  You also can see the fan speeds in the Z400 BIOS, and temps.

Here's a picture of what I'm using (but I mainly use the NA-RC7 LNA):

[Wesso]

Thank you all for your advice and suggestions!
So with your generous warnings I went ahead and decided to make the upgrade. It’s mainly because I got this HP Z400 at such a cheap price when I was prepared to build a new computer from scratch.

I ended up with a Fractal Design Define R5 case. As mentioned, by moving to a new case the HP Z400 PSU will not fit (as it’s not the standard ATX PSU size). Because of this I purchased another PSU, so in using a non-HP PSU, the power cable for the motherboard is now incompatible so an adapter is required, so I bought that too.

Moving the motherboard was alright, the HP Z400 has a backplate to it which cannot be removed so that went along into the new case. The motherboard is not the standard ATX fitting but it’s pretty close to it. 7 of the 9 screws aligned with the standard ATX motherboard mounting holes.

Fan wise this is what I did:
Front fans: 2 x 140mm fans at 1000RPM (3-pin) connected to Fractal Design Define R5 fan controller (i.e. controlled by voltage from PSU)
Bottom fan: 1 x 140mm fan at 1000RPM (3-pin) connected to Fractal Design Define R5 fan controller
Rear fan: 1 x 140mm fan (3-pin) 1200RPM connected to chipset fan slot (this will make the fan run at 100%)
CPU fan: kept it with stock HP cooler as I can’t be bothered to work around the 5-pin fan connection

I managed to connect the case’s front audio and USB to the motherboard and it works but at boot I am still required to press F1 to continue as it detected that the audio and USB is not connected. Can’t seem to get around this but that’s it with me as I intend to keep this computer on as a server.

All in all it’s been a great experience. I will admit that I came across things I did not expect given my experience has only been with building and tinkering with mainstream consumer computers, no workstations.

Thank you all and I hope anyone who is trying to achieve similar outcomes in the future will find this thread helpful.