EDITOR"S NOTES: Microserver Gen 8 Fan Control, Acoustics &
Two Step Forward... and one step back. The original Microserver
was a huge hit because it combined small size, high space and energy efficiency,
good enough performance, and low noise straight out of
the box. The relatively simple mods we devised to reduce the noise further
was icing on the cake. Our fan modding addendum, with details of the non-standard
4-pin PWM wire coding used by HP, probably helped sell a lot of Microservers,
especially to technical consumers for use as media servers in homes.
The new Gen8's intractable fail-safe fan/thermal shutoff system is draconian.
Any attempt to slow the fan, even applying a little friction by hand on
the fan's hub, is enough to trigger a complete system shutdown. There
is no hardware monitoring or fan control section in the BIOS; all this
is relegated to HP's vaunted ILO system, which as Larry pointed out, costs
Could the fan be replaced with a quieter one? The 6-pin, 5-wire fan is
so far from standard PWM fan configuration that even finding a plug to
fit the six tightly spaced pins was a challenge. After much scrounging
in the lab's old parts bins, I adapted an old 4-pin cable for audio directly
from a CD drive to the motherboard. The cable was cut in two and both
ends used with pins reconfigured so they made contact with the relevant
five pins on the motherboard fan header. The cut ends of the wire were
bared and tinned so they could be poked into the 4-pin female connector
of a standard PWM fan. Two of the wires from the stock fan are black,
so it seemed safe to assume they were both ground, which left 4 wires
to play with. I experimented with several PWM fans and umpteen combinations
of terminations, to no avail. No matter what I tried, the fans would 1)
not start, which led to the Gen8 shutting down before the end of the boot
sequence, 2) start at full speed, or 3) start at reduced speed but then
get into an annoying speed up/down cycle once in the OS and within a few
minutes result in a forced shortdown. After a couple of days of this,
I gave up.
The discussion thread "MicroServer
Gen8 is noisy" in HP's own forums started 08-15-2013 has 134
posts and remains active today, even though it was marked as "solved"
(by a HP mod?) on 12-04-2013. The problem is described thus:
If using AHCI or Legacy controller mode, fan noise will occur.
There is no possibility in lowering the fan speeds in this modes to
a lower value. It is going to be BIOS/iLO safe ranges.
The solution is "to configure the B120i in RAID mode. That
would mean configuring at least one disk as a RAID-0 array."
The end result, reportedly, is that the fan speed drops from about 37~39%
Never mind why fan control is tied to the storage controller.
The procedure to run RAID requires switching the B120i built-in storage
controller in Gen8 to RAID mode, then installing the RAID driver once
you boot into the OS from another drive. For those accustomed to the user-friendly
BIOS of consumer boards, this seemingly simple procedure in Gen8 is absurdly
complex, perhaps to chide you for not obtaining some server tech certification?
Getting the storage controller into RAID mode did indeed drop the fan
speed immediately to a lower speed, a little under 1200rpm as measured
with our calibrated strobe . It improved the overall noise quite significantly,
to a measured 19 dBA@1m SPL. With our standard four drive array in place,
the overall SPL was just over 20 dBA@1m, which is actually a bit better
than the original Microserver.
I did not repeat all of the thermal testing run by Larry, but tried some
load testing and noted minor increases in temperature on all the various
devices during routine use, no more than +5°C. Prime95 was run for
about 10-15 minutes, during which time, a bit of fan ramp up was noted;
when CPU temperature stabilized, the CPU was at 56°C (10°C higher
than during Larry's testing) and SPL was just under 21 dBA@1m.
The overall noise reduction in RAID mode compared to ACHI is around 10
dBA, or roughly half the subjective noise.
If you have no wish to run hardware RAID (whether because you prefer
one of the Linux distributions with its own file management system, or
you prefer leaving the drives as individual volumes) then running one
drive as RAID 0 is a viable option, though it can increase complexity.
The drop in fan speed and noise is most definitely worthwhile if you are
a SPCR enthusiast... or even if you just want your server to be reasonably
quiet without burying the box deep in a big closet.
Still, the absence of user-configurable fan control, the absurdly complex
5-wire fan, and lower fan speed being available only in RAID mode are
all strange annoyances. As one HP forum member posted on on 01-16-2014,
... because the old Microserver did not have iLO functionality,
it was able to regulate the fans (by measuring system and disk temperatures)
and now that the system has built in iLO functionality this ability
has been lost for non i120 controlled system usage?
I am sorry if I am asking uncomfortable questions, all I want
is that HP take this issue seriously and try to resolve the noise issue
in a way that satisfies cosumers who have come to expect and enjoy the
silent operation from previous HP proliant microservers.
As I said in a previous post, the biggest selling argument and
the reason I bought a new microserver is/was its silent operation as
it is meant to operate in a silent environment.