Z800 - Memory fan speed vs power cable /w temp sensor

[SoundChaser007]

Hello!

I have this z800 beside my desk with:

• two x5690 /w the performance heat sinks
• 96 GB of RAM /w heat-sinks
• the DPS-1050 DB-A 1150w PSU

I've faced a similar annoyance with an xw8600 (which I'm phasing out): the memory fans are just too loud.

I know that removing the memory shroud assembly is a Bad Idea. For the xw8600, I had replaced the stock memory fan with a beQuiet with good results. I can't do the same with the z800 due to its' byzantine memory fan assembly.

I've been running the system for about 24 hours without the memory shroud (again, bad idea, I know, this is science!) and my ears are much better. 

How can I validate the temp sensor attached to the power cable is functional without HP Performance Advisor? The temperature from the BIOS readings seems fine and Linux sensors is reporting the following measurements:

smsc47b397-isa-0480
Adapter: ISA adapter
fan1: 1800 RPM
fan2: 1776 RPM
fan3: 1304 RPM
fan4: 1271 RPM
temp1: +44.0°C 
temp2: +31.0°C 
temp3: +24.0°C 
temp4: -128.0°C 

Is it sufficient to diagnose that the power cable-attached temp sensor is functional? The -128 degrees value seems iffy but perhaps that register is simply unused?

Thank you for the support!

[DGroves]

the normal fan sequence on a cold boot is as follows

power on, all fans (case and cpu ) at low speed

within a few sec the case fans ramp up to full speed

fans remain at full speed for approx. 2-3 sec then ramp down to  whatever the bios fan speed is set to

your bios temp reading of -128 temp is indeed indicative of a failed ambient temp sensor which is located in the main power cable near the small power on  button/led circuit board covered in heatshrink  where the bundle of wires exit the heatshrink it's a transistor which can be replaced with a 2n2222a Plastic (not metal) TO-92 case   note that the transistor will have two leads of it's 3 leads connected together simply check the number of the existing temp sensor transistor to get it's pinout and then duplicate the  same on the replacement

https://components101.com/transistors/2n2222a-pinout-equivalent-datasheet

finding a z800 power cable nowadays can be challenging which is why repair might be your only option

i've posted on this subject several times over the years search the forum for my previous posts that go into detail on this subject

https://h30434.www3.hp.com/t5/Business-PCs-Workstations-and-Point-of-Sale-Systems/z800-fan-speed-and...

[SoundChaser007]

Thank you DGrooves!

Actually, for the record, I disabled the annoying fans going all the way up during boot process by switching the controller type from RAID+AHCI to AHCI (or even disabled) in the BIOS. Silly, I know.... it appears to be weird xw8600 issue that's present in the z800 BIOS as well. Much quieter boot process now.

I can manually crank up the *CPU* fans speed' by either giving the system a load (Gentoo being a source-based distro is great for that) or playing with the BIOS setting. 

The memory fans seems also to adjust themselves accordingly, so somehow the system doesn't consider its internal temperature to be worth going full throttle. The noise from the memory shroud remains annoying - the fans themselves are within nominal parameters from an industrial standpoint. Residential standpoint, less so.

The HP z800 thermal management being quite sophisticated, if I got it correctly, the possibly failed temp sensor contributes to the fans speed (all of them? just the memory fans?)

Before going the repair or part hunting, I'd like to confirm it's really caused by this part failing. Is the only way to really get to the bottom of this without using electronic measurements being the Performance Advisor app, or are BIOS readings (not Linux sensors) enough?

Thanks again!!

[DGroves]

please reread what i previously wrote

on the z800 the ambient air sensor controls the case fans

the cpu and memory fans are on a different sensor circuit got it now?

loading the cpu(s) will generate more heat, more heat means case fans will increase speed when temps rise to set threshold

a defective ambient air sensor can  cause fans to go from slow to full speed instead of gradually ramping up in speed as internal air temps rise

changing the bios setting from AHCI+Raid  to AHCI will have no effect on the ambient air temp sensor when the system is working normally and should not affect it even when the sensor has failed

when selecting AHCI+Raid it simply means that the raid code is available but unused (not loaded)  until a raid array is defined

and again i repeat,............... a negative 128 air temp indicates a failed ambient air temp sensor which is usually the transistor temp sensor in the power cable

[SoundChaser007]

Thanks for your patience, I know this was brought up many times - I'm doing the homework and I did read and re-read 🙂 Remember this is science, so I tend to question everything 😀 and this should (hopefully) lead to a better understanding.

Rebooted the monster.

BIOS in front of me.

First the trivial BIOS twiddling stuff - skip if you want. Just sharing my observations; I think they could be of general interest to other z800 owners:

I do confirm that during POST the fans go up as mentioned and quickly come down.

I also confirm that I did the set "SATA Emulation" to "IDE" and I know it has no impact on the fans control per se. Disabling RAID+AHCI this way simply turned off - by side effect - the fans going all the way up during the init phase, after POST.

It could be related to the additional load put on the CPUs while loading the RAID code. Anyway, anyone reading this thread, if you don't use the onboard controller, changing this setting does quiet things down during the init phase. That's it - I did not expect any other gains from that setting than quieter pre-boot sequence.

Back to sensor stuff.

The readings shared previously where from the sensors app which may not know how to read all sensors registers present in the z800 as its limited to what the Linux kernel modules cover. Alas, I don't have readings from HP Performance Advisor to compare since it's Windows only.

From the BIOS, I see the following values from "System Temperatures". Can you confirm whether these values are exhaustive from all the system's sensors?

CPU0 and 1 at 30C

Ambient is 23C (is it from the power cable sensor?)

Memory is 49C

Tachs are:

CPU0 1125rpm CPU1 1008rpm

Memory (plugged it back) 1620rpm (!!!!)

Chassis 1801rpm (!!!!)

PCI 1325rpm

Chipset 0rpm (there's no fan on the chipset)

From these readings, do you think the issue is still the sensor on the power cable? I mean, that would make sense if the readings from that sensor do not correspond to the values seen in the BIOS and simply aren't reported there (perhaps that's what you meant by "different sensor circuit"?)

However if they do correspond to the ambient temperature sensor, confirming that the sensor is functional, why are the tachs so high?

[DGroves · Accepted solution]

 the z800's built in bios monitoring capability to check fan speeds is?

and again to clarify, changing "ANY" the bios's HD settings such as the default AHCI+RAID to IDE has absolutely no effect on the systems fan speeds period!!

the memory fan speed of 1620 is a acceptable speed (the max speed is 3500) the memory fan speed is dependant on the number of dimms installed as a system with all ram slots filled will generate quite a bit more heat than one where every other slot is filled

and yet again!!! you ask if the cpu temp/fan is controlled by the ambient sensor even though I SPECIFICALLY STATED IT IS NOT

none of your listed temps is excessive, the only reason i stated you may have a failed ambient sensor is because you previously stated you had a report of the ambient temp being -128 if this is not so then you have no issues with the system

and before you ask more questions  please take the time to reread my previous replies before posting yet again a question that has been specifically answered in detail previously

[SoundChaser007]

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@DGroves wrote:

 the z800's built in bios monitoring capability to check fan speeds is?

Correct, it "is". 

https://h30434.www3.hp.com/t5/image/serverpage/image-id/170366iDD148F609C4075E6

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and again to clarify, changing "ANY" the bios's HD settings such as the default AHCI+RAID to IDE has absolutely no effect on the systems fan speeds period!!

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OK

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the memory fan speed of 1620 is a acceptable speed (the max speed is 3500) the memory fan speed is dependant on the number of dimms installed as a system with all ram slots filled will generate quite a bit more heat than one where every other slot is filled

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AH! So it's the number of DIMMs and ambient temperature reading that perhaps provide a baseline for the fans' speed. That's the information I was looking for from the start. I'll quote myself:

the memory fans are just too loud.

I'm sorry if you thought I was asking about CPU and case fans all this time (probably most people do) - I wasn't. I thought I had made it clear by starting with that in the discussion title, too.

and yet again!!! you ask if the cpu temp/fan is controlled by the ambient sensor even though I SPECIFICALLY STATED IT IS NOT

Respectfully and politely, I asked about the effect of the ambient sensor on the memory fans.

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none of your listed temps is excessive, the only reason i stated you may have a failed ambient sensor is because you previously stated you had a report of the ambient temp being -128 if this is not so then you have no issues with the system

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Thank you for confirming!

For anyone who reads this thread, always refer to the BIOS' System Temperature readings to validate whether the ambient sensor is faulty and DO NOT trust the -128 reading from the 'sensors' app.

I'm done with questions! Next time might be about a Z440 😉