-----Original Message-----

Date:    Thu, 15 May 2008 08:43:56 -0400
From:    LAWRENCE LASKOWSKI <[log in to unmask]>
Subject: CPU Fan noise

I just put a new CPU  in my old Dell 8400. The computer was a little =
dirty inside and  I blew all the dust out as best I could.  =20
The computer was never this noisy, That I can remember.=20
The fan seems ok , no play in the bearings est..
Could I have hooked something up wrong and it thinks its warmer than it =
is?
The air seems nice and cool coming out the back. Blowing very hard at =
times sounds
like a jet to what it was before.=20
All I did was blow it out good remove the shroud and heat sink ect.just  =
replace the=20
CPU.
By the way old CPU was a P 4 3.0Gz  to a P 4 3.8 GHz

Thanks

Larry

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------------------------------

I have a Dell 8400 as well and mine shipped with a Pentium 530 (3.0GHz)
processor - probably the same one you had. The Thermal Design Properties of
the 530 are 84W, meaning that under maximum load, the CPU will 'consume'
(thoretically) 84 Watts. This is important as the cooling solution provided
is for that wattage.

Your new 3.8GHz processor has a TDP of 115W. Not only is it using more
electricity, it will run hotter also. I suspect that the fan is woking
harder to keep the new processor cool. The fan is dynamically controlled by
the motherboard - it probably is an Intel 925x -  (which has certain built
in monitoring features disabled  - read Dell proprietary) in order to adjust
the fan speed according to load. As long as you reattached the heatsink
correctly and used a good thermal paste, or at least the proper amount of
some, you should be OK. The stock heatsink is actually pretty good (a tower
heatpipe) and the fan shroud helps to funnel in air over it pretty
effectively.

The only concern would be the extra load on the stock power supply. (should
be a 350W PS) As long as you don't have too many added in extras (HDD's,
sound card, upgraded video card, etc.) you should be OK. You may just have
to live with the additional fan noise. I've looked for replacement/upgrade
fans but could not find anything that would support the temp monitoring
feature using a 3-pin attachment (of the same fan dimensions). The stock fan
has a built in diode that measures the temp of the air blowing through it
and sends a signal to the mobo to increase or decrease the voltage to the
fan, increasing or decreasing its rotational speed.

When I upgraded my processor, I ultimately chose a Pentium 650. It has the
same TDP as the 530 but with 2Mb of L2 cache insted of the 530's 1Mb. (plus
an extra .4Ghz)

HTH

Chris Ryan

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