Noisy OCZ GameXStream PSU

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A newly installed OCZ GameXStream 700W power supply
is annoying noisy, much noisier than the basic 450W
Cooler Max it replaced.  It is quiet enough at startup but
the fan quickly gets to what seems full speed.

Most of the reviews on NewEgg laud it for quietness but
a few had the same noise problem I do.  Those that
replaced the unit thinking it was defective found the same
noise problem with the replacement.  Do some systems
just provoke this noise?  In my case, the CPU is just below
the power supply.  Exhaust is only a bit warm.


    MB: A7N8X V2 Deluxe
    CPU: AMD 2800+ single core, 32b
    Mem: 1GB (1 x 512MB, 2 x 256MB)
    HDD: 1 250GB, 1 400GB, 1 160GB
    1 x CD/RW, 1 x DVD/RW
    Full Tower


Re: Noisy OCZ GameXStream PSU

On Sat, 26 Apr 2008 01:41:49 -0400, "Gary Brown"

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If it's working properly the fan speed is a function of the
temp the internal sensor, senses.  If the case doesn't have
a fairly unobstructed, open rear exhaust fan area and ample
front intake area, it will tend to reduce PSU exhaust rate
and increase intake air temp, resulting in higher temp
inside.  If the sensor is mounted against a heatsink there
may also be some variability in manufacturing, exactly where
and how well the heat is transferred from the 'sink inside.
Similarly a higher room ambient temp will result in higher
PSU internal temp.

Beyond the case and it's potential modifications, another
option is to void the warranty by opening the PSU and seeing
if you can locate and relocate the fan sensor - if it's the
latter issue, if the former it would not be advised to
countermine the intended cooling as it may decrease
lifespan.  The last alternative is to reverse engineer the
fan control circuit and change some values to result in
lower speed, replace the fan with one having lower default
RPM, or place an inline current or voltage limiter on the
fan's power leads.

One other thing to keep in mind.  Your system places a
significantly higher load on 5V rail due to the A7N8X
motherboard, while many place a higher load on 12V rail
instead.  The result can be that your 12V rail voltage level
inside the PSU is higher than in a (newer) different system
and this results in higher voltage if/when all else is equal
in your system versus someone else's.

We can only assume the manufacturer has made no changes to
the PSU design - it is possible they had encountered more
RMAs than they'd like and decided to increase fan
speed/response to heat.  It is even possible that random
variations in resistors used in the fan control circuit
cause a higher bias in the circuit and a little higher fan
speed (though this seems like it would typically be less of
an increase than most people would notice).  

Surely there are other factors I can't think of at the
moment as well, which of these things is the primary cause
is up to you to determine, though it could be a combination,
each contributing a little bit.

Re: Noisy OCZ GameXStream PSU

Gary Brown wrote:
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My guess would be, the A7N8X uses +5V for processor power. On
my system, Vcore uses 16 amps and my video card uses 5 amps
(only under highest gaming conditions). On the 5V at 30A rail,
that is a little over 2/3rds of the capacity, and we're not
counting drives yet. On the other hand, the massive
12V capacity is hardly being used at all.

The 3.3/5V has a combined power limit of 155W. If that was a
thermal limit, it could be that the 3.3/5V part of the design,
is getting hot, and causing the fan to run at a higher speed.
But because the 12V has next to no load, the actual air stream
is cool.

It all depends on whether the fan speed is set by heatsink
temperature or air stream temperature, as to whether it is
appropriate for the fan to speed up.

I would try the power supply on a more modern system, one with
massive 12V loading, and next to no 3.3/5V, and see if the
loading pattern causes a lower fan speed.


Re: Noisy OCZ GameXStream PSU

Gary Brown wrote:
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It probably just has a loud fan.  The GameXstream is made by Fortron-
Source, whose PSUs aren't known for quiet.  Both of my 500W Antec
Basiqs, which are also made by Fortron (Epsilon series?), each have an
80mm fan that's annoying even when the PSU is cool and only 6.0V is
being fed to it.

Re: Noisy OCZ GameXStream PSU

On Sat, 26 Apr 2008 10:03:12 -0700 (PDT), "larry moe 'n

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Ok, but comparing higher RPM/noise of 80mm rear fan to 120mm
bottom fan is apples and oranges.

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