HP Z840 Motherboard Auxiliary Fan and Cooler Header Volts and Amps

[Robert979]

Due to the density of hard drives I have added to the workstation, I am having cooling issues and would like to add some additional fans using the available motherboard connection points: 23, 25, 26.  I have been searching but unable to find documentation or information on the auxiliary fan header connection at port 23 on the motherboard, and the CPU auxiliary cooler connections at ports 25 and 26 on the motherboard. I want to connect additional high CFM (~ higher amp) cooling fans but want to be sure of the amp limits of ports 23, 25, and 26 and verify that all three connection points are 12 volts before purchasing any fans.

[DGroves]

the z840 was designed from the very beginning to have the ability to properly cool the system when it was fully configured with pc-e cards and 3.5/2.5 drives (or SSD's) so i doubt you are actually overheating the system.

if absolutely necessary you can increase the cooling profile from within the bios and set the default fan speed to a higher setting

also if you want help with a suspected issue/problem then stating the installed hardware and system config is required due to readers here lacking the remote viewing ability to remotely see your system config

i personally use/service these systems with all 4 internal hotswap bays filled and 4 to 8 more 2.5in drives in the 5.25 external bay(s) and dual PCI-E SSD cards 128GB ram and a firepro w9000 video card (which draws about 230 watts when rendering) and i don't have cooling issues in a normal office or home environment 

the 4 pin headers by the CPU(s) are for powering the water cooling pump and are not suitable for fan control and may not be able to supply the same current as a dedicated fan header

since HP does not document the fan header current limits, or how many fan headers on a 12v line i would limit the total fan(s) draw to under 1 amp

note that most boards makers will often put 2/3 fan headers on the same power line which means that the total draw of both headers must still be under1 amp although premium boards may have a higher current raiting

[Robert979]

     Thank you for the feedback.  Sorry for not being more precise in my original description of the problem, but the goal was to find out the unpublished voltage and amperage limits of the fan header ports on the motherboard, not to question the HP’s engineered cooling for the standard workstation.  If at all possible, my goal is to keep the BIOS fan settings on auto instead of changing it to a higher setting and to just increase the airflow with additional fans.  Thank you for the 1 amp planning factor.  I had seen some comments online about some high-end motherboards having higher (3 amp) fan header limits, and was hoping HP workstations might be included, though the only named motherboard I saw was SuperMicro.

     To elaborate further on my actual problem, I have installed this hard drive cage, FatCage MB153SP-B, into the bays below the slim-line optical drive.  I have three WD Red Pro 4TB hard drives installed in the cage.  The heat/cooling issue I am having is for these three hard drives.  The OEM fan has 38 CFM and 3.38 mm H2O pressure.  I changed this fan to one that has 64 CFM and 9.73 mm H2O pressure, which has helped, but the drive temperatures are still not where I want them.  Considering whether I should continue to purchase and test higher CFM/pressure fans attached to the drive cage or look at other options, I have added two of these (StarTech.com Expansion Slot Rear Exhaust Cooling Fan with LP4 Connector, 7 CFM and unknown pressure) in the open PCIE slots to see how increased heat exhaust might help, but based on the results don’t think the fan CFM and pressure is high enough to be useful.  My next test will be to replace the 64 CFM drive cage fan with a blower fan (on the way) that has 46 CFM (lower) and 74 mm H2O pressure (higher) and direct the exhaust into the PCIE lanes instead of into the CPU/RAM fan shroud.  I am hoping the blower fan will avoid any turbulence caused by the current fan exhausting into the CPU/RAM fan shroud and the increased pressure will do a better job of pulling cool air across the three drives.  My follow-on test (and the reason for my original post) will be to add some higher CFM (27)/pressure (45)/amp (.62 each) 40x40x28 fans in the PCIE area connected to the 4-pin fan header port 23 to exhaust heat better, including heat now being redirected using the blower fan mentioned above.

     If anyone else has tried to solve this same or similar problem, I would definitely be interested to hear what you tried and how it worked.  Or if you have any feedback on the tests I have run so far or the upcoming planned tests.  Thank you very much for your time.