Re: xw6600 xw8600 fans way too fast and loud, solved (5227 Views)
Honored Contributor
Posts: 659
Registered: ‎10-16-2006
Message 1 of 4 (5,238 Views)
Accepted Solution

xw6600 xw8600 fans way too fast and loud, solved

[ Edited ]

This is one of those "who would have thunk it" issues.  My xw6600 arrived yesterday from eBay; fired it up and all sounded good until about 4 minutes in and all the fan RPMs ramped way up.  Very loud.  Reminded me of the posts a bit back about the xw8600 that had loud high rpm fan(s). Let things cool down over night, and booted into BIOS to check settings...... all good, with thermal set to lowest value, and in the first BIOS column the temp and fan speed settings all looked good, and the fan RPMs were back to normal.


About 5 minutes later, back to high RPMs for all fans suddenly.  Checked back to the BIOS speed/temp info area (this is available in BIOS on the 6600/8600's, but is not in the 6400/8400's BIOS).  The "Ambient" temp reading had gone from normal stated 16 degrees centigrade to 70C (about 160F).  Obviously, the room was not that hot.


By chance I had happened to have bought an extra HP xw series front cabling set off eBay previously.  That cable includes the on/off switch and wires, the front on/HD led leads, the speaker wires, and a few more items.  My xw6400's front cable did not have an ambient air temperature thermisitor bundled into that cable, but I had noticed that the one I had bought did.  A search on the cable's HP serial number showed it was for an xw8600, but it worked ine on a xw6400 when I tested it in one.


With the knowledge that the xw6600/xw8600 series have an ambient air sensor built into that cable I postulated that the original cable in my xw6600 might have a bad or loose sensor that was feeding correct info to the motherboard only when really cool, and once things warmed up the sensor incorrectly reported that the room air temp was 70C (158F).  Then, the motherboard would respond by ramping up the fans to their full rpm's rather than the lower values they normally run at.


Here's a listing of fan title, with rpm's at normal and then at the "70C/158F" temperature, from the BIOS readout from the xw6600.  Note that the xw8600 will only list one chassis fan (rear exhaust case fan) :


CPU0         1222               When abnormally ramped up:  4941

Mem           1625                                                                       3045

Chassis    1355                                                                        3118

Chassis    1331                                                                        3247

Chipset      3704                                                                       8359


Interesting problem, and one that a motherboard transplant would not have fixed.


For those of you who use HWMonitor, my favorite free temp and fan rpm prober, this event allowed me to determine that for the xw6600 the "TMPIN2" listing there corresponds to the ambient temperature thermisitor.  Attached is a pic of what HWMonitor results look like when the thermisitor in that cable is working properly, and I'll try to add in a pic of what it looks like when the thermisitor is incorrectly reading too high.


If you choose to download HWMonitor from get the free one and choose no when the installer asks if you want to install the toolbar stuff.

Honored Contributor
Posts: 659
Registered: ‎10-16-2006
Message 2 of 4 (5,227 Views)

Re: xw6600 xw8600 fans way too fast and loud, solved

[ Edited ]

Update:  After unplugging the original front on-off switch/ambient air sensor/led leads/speaker wires xw6600 cable assembly from its motherboard connection and hooking up a spare one (just hanging out of the side of the xw6600 to test my theory) I reconnected the original cable.


The problem of the ambient room air being incorrectly reported as almost 160F went away, and has not come back so far, for days.  My guess is that there was some oxidation on the contacts from the original thermisitor's two leads resulting in bad contact, now rubbed clean by my disconnecting/reconnecting the main connector at the motherboard end of the cable.


The fact remains that if your xw6600/xw8600 fans are running way too fast/loud do check the ambient temp readout in BIOS (or with HWMonitor under the TMPIN2 listing) to see if an incorrect reading is causing the issue.  If so, try disconnecting that cable's long black connector and reinsert, or swap in a known good replacement, which is pretty easy to do.


There is a good company selling this part on eBay right now, 12/11, for $5.74 each, free shipping, under the xw6200 section but that part is actually for the xw8600 and it will work fine in the xw6400 and xw6600 also.  It just is a bit longer than the ones that come with the 6400/6600, and its part number is 349576-006.


I have bought a number of spare parts from them in the past...... A+ company, in my experience.  That was the original source of the spare one I had available for testing.  By the way, the xw6400 cable does not have the thermisitor built in, but this cable works fine in it anyway, and the added thermisitor is not detected by the xw6400 motherboard..

Honored Contributor
Posts: 659
Registered: ‎10-16-2006
Message 3 of 4 (4,910 Views)

Re: xw6600 xw8600 fans way too fast and loud, solved

[ Edited ]

Newer update...... the problem in fact did come back so it was not an oxidation issue.  Rather, it was an intermittent bad thermisitor out on the end of that on/off cable assembly.  I finally replaced the original cable with the spare new one from a xw8600 noted above (HP part number 349576-006, extra long, but that was fine) and the xw6600 has worked great ever since.



Occasional Visitor
Posts: 1
Registered: ‎11-11-2012
Message 4 of 4 (4,374 Views)

Re: xw6600 xw8600 fans way too fast and loud, solved

Hi. I recently purchased a couple of HP xw 6400 workstations in Craigslist.  A week ago one of the chassis fans went mad spinning at 4600 RPM, for no reason. After researching and following your threads, I updated the bios, disconnected the cmos battery, etc, etc, the problem was still there.


Not long ago I tried to upgrade the cpus for 2 quadcore E5345, as they were supposed to be the highest compatible ones, but then I discovered, sadly, that some 20% of XW 6400 don't take them. By then I had already swapped the cpus in the sockets so many times that the motherboard went crazy and didn't even initialize at all.


Desperate, I tried one last thing. I had some experience with old desktop computers and knew that some residual electricity issues can be solved by completely unplugging the power supply cable for a whole day. In this situation (the motherboard not responding) I did something similar, I unplugged the motherboard from the power supply in the machine. (It's a flat connector on the lower left corner of the motherboard that has something like a plastic string to pull from).




Same with the fans. I tried everything, applications that monitor the speed, etc, etc, nothing worked, there's nothing the bios settings can do, I even tried to go all the way up to force both fans to the max speed, nothing.


I simply unplugged that connector and no problems ever since, it runs quiet and smooth as if never had ever happened.


Why this happened? because the motherboard seems to be highly sensitive to any new hardware you install and I did install a hard disk drive.


I hope this can still help anyone out there. Thank you all for your previous comments.

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