HP xw8600 workstation fans run at max all the time after upgrading CPUs and memory

Question

Hello, This is my 1st post on the forums here so I would like to thank everyone for the help ahead of time. I have an HP xw8600 workstation on which I have upgraded the CPUs and RAM recently - after the upgrade the fans seem to spin at full speed all the time (not just under load). Before the upgrading the fans were barely heard but afterwords the workstation has become very loud. This seems odd that the fans always run fast now and seems like this is not "normal" - what needs to be done to allow the fans to again be modulated by load/temp settings as designed? I looked in the temp and fan RPM settings in the BIOS and it looks like all sensors are working (including ambient temp sensor - was stating around 20 deg. C). Hardware changes:Before - CPU: 2x Intel Xeon X5460/ 3.16 GHz, 12MB L2, 1333 MHz, FSB,120WRAM: HP 32GB (16x2GB) DDR2-667 ECC FBD RAM - using RAM riser After -CPU: 2x Intel Xeon X5492/ 3.40 GHz, 12MB L2, 1600 MHz, FSB,150WRAM: HP 32GB (8x4GB) DDR2-800 ECC FBD RAM - using RAM riser NOTE: From the HP spec sheet it says that 32GB(8x4GB) is not supported by 5492... I am not sure why this is so and do not know if this has anything to do with my fans running very fast. HP 32GB(8x4GB)DDR2-800 ECC FBD RAM RISER Supported ONLY w/dual processors
5272, 5472, 5482 HP 64GB (16x4GB) DDR2-800 ECC FBD RAM Supported ONLY w/dual processors
5272, 5472, 5482 and 5492.
Acoustics waiver required. Other than the constantly loud fans the workstation works perfectly with the new setup. Please let me know if anyone has run into this issue with the fast fans and whether there is a fix for this (maybe flashing BIOS?). Any advice is greatly appreciated! [I originally posted this under Desktops section - http://h30434.www3.hp.com/t5/Desktop-Hardware/HP-xw8600-workstation-fans-run-at-max-all-the-time-after/td-p/3929746]

Answer 1

The xw8600 has a motherboard firmware setting that if it detects high powered processors in place it wants to see the "double tall" performance heatsink/double fans per heatsink in place.  I have posted about that and how I rewired a double tall to use side by side in my xw8400 next to a single tall heatsink/fan to see how cooling was affected in that workstation. The xw8400 did not ever come with double tall performance heatsinks, to my knowledge, so its motherboard's firmware is different. In those posts I also explained how to do a simple jumper wire modification on a single tall heatsink to spoof the xw8600 into thinking it had a double tall/two fans in place over each processor.  Simple and quick. So, you might want to get a couple of double talls off eBay, or try the jumper wire trick.  I'd personally advise to get the double tall heatsinks given that you're running 150W max TDP processors.  If I remember correctly HP wanted you to use the double talls for 120W max TDP and above.  I'd feel comfortable using that trick on a set of 120 watt processors if I was not hammering them frequently, but it sounds like you're a high level power user. The all-fans-on-high can be due to a failed thermisitor in the front power cable reading ambient air temps too high, but you can check that in BIOS to see the temp and it sounds like yours is not elevated incorrectly.  You can search for my experience with that in a xw6600, and it is an easy $8.00-$12.00 fix with a new cable off eBay.  You'd want the longer version for the xw8600, versus the shorter one for the xw6600. Finally, maybe you've just gone too high in your total wattage use?  Those risers can run hot and draw lots of power.  Could you live with less ram and get rid of the risers using 4GB sticks?  Sometimes those prior prohibitions regarding what is and is not supported go away with later BIOS updates.  Is your BIOS the latest? Welcome, and let us know what turns out to be the problem so others can benefit too. Scott