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Sivoba
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Replacing z820 rear case fans with regular 4-pin pwm fans

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Z820
Microsoft Windows 10 (64-bit)

Hi,

I recently ordered some Noctua Fans to replace the case fans in my z820. Since the Noctua Fans have a standard 4-Pin Pwm connector I now have the problem, that I can easily switch the 2 front system fans but not the dual rear system fans because of the special 6-Pin connector. Is there an adapter or at least a wiring diagram for the 6-Pin connector? 

greetings

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DGroves
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Message 10 of 21
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yes there is, the z820 rear fan pinout is the same as the z800

 

and both the z800/z820 models have their manuals posted online which includes this information

 

please download the z820 service manusl for future reference

 

 

https://support.hp.com/us-en/document/c01718096

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SDH
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Looling on eBay for "Z820 rear case fans" shows that the dual rear case fan system HP has designed for the Z620/Z820 is comprised of two 4-wire PWM controlled 92x92x25mm fans with fan number 644315-001.  There is either a set of two Delta or two Nidec fans that make that kit up when combined with the black plastic dual fan holder (which will have its own part number embossed on its surface).

 

HP has used the same fans with different part numbers.... so if you look up the manufacturer's code on the fan you can find other HP fans that use the same code as a single 4-wire fan.  Look up:  Delta QUR0912VH or NIDEC T92T12MS3A7-57A03.  Note the Delta draws more amps and thus might run faster and louder.

 

HP PWM 4-wire fan pinout is always ground, 12vdc, rpm sense, pwm control for pins1 to 4, and there may be a ground jumper from pin 1 to pin 5 to tell the motherboard the fan is part of a "Performance" heatsink/fan.

 

Each of the bonded pair of fans for the rear exhaust kit has its own 4 wire output, but they end up leading to a single white 6-pin plug end.  Two wires out of the 8 total are bonded half way towards the plug end, and you just need to dissect a set to figure out which wires they combined.

 

Now, why even do this?  I very much like the Noctua hardware but the problem with your idea is that HP has carefully balanced all of the fans together.  Replacing one set with Noctua will imbalance your system.  Example, and why I tried and gave up on the idea:  Noctua fans are designed to run relatively slow to begin with.  HP fans are designed to run very fast if they receive 12VDC and no PWM braking.  The HP PWM control is embedded in the motherboard's firmware.  Put in a slow Noctua and give it the HP PWM braking and it will go from slow to too slow. 

 

Speed up the too slow Noctua fans via BIOS?  Good idea, and you'll boost the Noctuas nicely but also boost the other non-Noctuas too, too much.

 

I went back to using the HP fans, and I fine tune them as needed with the Noctua RC7 and RC6 4-wire fan speed reducers.

 

Let us know once you figure out the 2 x 4 = 6 pinout......

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muze
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I went back to using the HP fans, and I fine tune them as needed with the Noctua RC7 and RC6 4-wire fan speed reducers.

 

Hi SDH,

 

Could you please expand on these i.e can they be used with the standard z620  front and back case fans?

 

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SDH
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The way PWM fans work is that they have 4 wires with pin 1 providing ground, pin 2 providing 12VDC, pin 3 sending motor RPM feedback info, and pin 4 receiving PWM throttle signals going out to the motor.  HP PWM fans use that same process.

 

The Noctua fan speed reducers simply add in a high quality resistor onto the 12VDC line so the voltage getting to the motor is reduced.  All the rest stayes the same, and thus the HP motherboard control of the fan stays proportionate.  The fan'r RPMs are reduced at its baseline, and the same % PWM speedup or slowdown gets applied from the motherboard as if the fan was receiving 12VDC.

 

Noctua has a number of these, but pretty much the only ones I use are the NA-RC6 and NA-RC7.  The RC6 has a higher rated resistor (thus, slower baseline RPM results) and the RC7 a lower rated resistor.  They also make 3-wire adapters.

 

Some HP fans use 4-pin plugs with the standard type of white PWM plug morphology.  some use 4-pin plugs with no central standard ridge.  Some use 5 pin plugs wihtout or with a pin 1 to pin 5 ground jumper.  Some are more complex with two fans being run off of 1 plug.  So, you need to be willing to fiddle to change things around using this method to a lesser or greater degree.

 

The later workstations from HP have been better in noise control.

 

The NA-RC6 have been harder to find but I recently got a stash off Amazon.....  Noctua sells a 3 pack of the NA-RC7 as NA-SRC7.  Google noctua LNA and noctua ULNA for added info.

 

On the Z600 and xw6600 there is a small too fast northbridge heatsink fan that I always add a NA-RC6 to, and it is a perfect fit because it uses the standard PWM plug type, and that fixes a major source of unnecessary noise in those two workstations.  I've always added a NA-RC7 to the front PCI fan in the earlier HP workstations, but with the Z600 and Z620 HP started using some front fans that are quiet as is (the lower amperage Nidec instead of the higher amperage Delta).

 

Edit:

 

Google gives some added info:

 

NA-RC6 = 80 ohm resistor

NA-RC7 = 50

NA-RC9 = 100

NA-RC8 = have not found

 

The LNA (generally the RC7) reduces 12VDC to about 8.5V, while the ULNA (generally the RC6) reduces 12VDC to about 7.3V.  This holds true for both the 4-wire and 3-wire versions.  You want the 4-wire version to pass PWM, however.

 

Again, slow running Noctua PWM fans with the HP motherboard's added PWM slowing mechanism (even applied at the baseline speed) generally results in Noctua PWM fans running too slow in a HP workstation.  I have used some of the non-PWM Noctua fans out front with 3-wire LNA adapter for my PCI fan if I've needed to add one in the older workstations.  Very quiet, running a little under 1000 RPM.

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muze
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Many thanks SDH for the very detailed reply, really appreciated.

 

I've just bought Dual xeon e5 2665 z620 and tbh i'n quite disappointed with noise level.

 

So i did look around on here and came to the conclusion that replacing the rear 2 and front case fans with noctua is a no goer:(

 

i've tried to find out what the pins are on the case fans but not been able to find anything apart from ebay selling a front fan unit stating it was 4 pin.

 

I spoke to a company selling fans etc and they said ask HP if their fan connectors/leads are generic or their own, but so far i've tried calling HP support 4 times and they can't give me a definitive answer.

 

What options do i have to bring the noise levels down, bios, replacing fans etc?

 

 

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SDH
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Well, if you're lucky someone turned the PWM fan speeds up in BIOS and all you'll have to do is turn that back down to the lowest setting.  It is easy to find in BIOS.  Most of us keep that at the lowest  value.  Some turn it up for very processor intensive projects and then turn it back down when done.  Maybe the prior owner forgot to set that back to baseline.

 

Search eBay for Z620  and Z820 rear case fans and also for same for Z600.  They all have a HP combined 6-hole plug for the fan pair plugging into a 6-pin motherboard header.  The fans all appear to be interchangable.  You might wish to experiment with the Z600 set first..... the wires look more color coded.  Regardless, you can be virtually certain HP did not change how they combine the 8 wires coming from the fan motor's sides to a single motherboard connector.  You can splice in a single RC7 resistor to each of the 12VDC wires and you'd be good to go with your test setup for about 20.00 total.  Check BIOS first, of course.

 

Front fan.... 4 wires, standard wiring order, just get a RC6 or 7 and shave off its center ridge on the plug.  Keep the side ridges.  I posted in here on how to get HP type plug ends from Mouser.com.... 4,5,6 hole plugs are all available.

 

Front fan for the Z820 is 647113-001 and Rev B is Nidec .35A.  There are Delta ones too that I believe run higher amps and thus likely would run faster and louder at baseline.  Same idea for the two bonded rear Nidec fans 644315-001..... go look up both of those on eBay.  Note HP might use the same fan as a single one up front or as a bonded pair in the rear.  It is not that complicated because these are pretty standard fans.

 

Edit:  Checked.... the two Z600 rear case fans come as a bonded pair and are mounted in a plastic fan holder, versus the Z620 two bonded rear case fans come as a pair but are not in a plastic fan holder..... they are connected by the wires and each is just screwed onto the rear of the case.  Don't know about the Z820 right now.  Regardless, looks like the same fan bonding method is used so you can modify them at will.

 

 

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muze
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Thanks SDH for that detailed explanantion.

 

I have ordered a pack of 3 of RC6, can I use these for all the 3 case fans?

 

Also, can you use RC6 for ALL the fans inside the z620, or would I need to use RC7 for non case fans?

 

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SDH
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I'm assuming this means you checked in BIOS first and overall fan speed was set to the lowest value there.

 

The answer is theoretically yes, but I don't do anything to the fan in the power supply or the heatsink fans.  From prior reading there are some voltages below which the PWM system does not work well, so the higher resistor value in the RC6 4-wire ULNA may be too much..... I'd get a stash of the lower resistor value (higher voltage) RC7 to have available, and I'd start with the rear case fans first.

 

Getting a Z600 rear case pair to work with first might be best.... they have the wires color coded rather than all black so figuring out what HP did will be easier with those.  Let us know......

 

Find a fan/temp utility to monitor things with.  I use HWMonitor but the later HP workstations don't show all of their details with that.  You need to monitor things closely if you choose to experiment like this.

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muze
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Thanks SDH for the quick reply.

 

I haven't had a chance to play with the machine i.e BIOS etc, been away.

 

Saw the RC6 set so i ordered it.

 

In a nutshell, the RC6 is good for the 2 rear case fans and the front case fan?

 

I will order some RC7 too.

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DGroves
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Message 10 of 21
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yes there is, the z820 rear fan pinout is the same as the z800

 

and both the z800/z820 models have their manuals posted online which includes this information

 

please download the z820 service manusl for future reference

 

 

https://support.hp.com/us-en/document/c01718096

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