SPCR

1) Have you read the P4 quieting article? Look under mods & projects in the main site.

2) Your mobo fan control interests me, Please remark with more detail here: http://forums.silentpcreview.com/forums ... php?t=2175
Is it adjustable via BIOS?

3) http://www.siliconacoustics.com/pabst84122ngl.html might be worth a risk -- Papst fans can often be "clickers". Otherwise, look for a Panaflo w/rpm sensing. Hard to find. Check posts in the fan area and see if there's any links suggested.

4) Sparkle - fan swap usually works well. Don't know about thermistor control -- usually if the PSU has it, there's some ref to it -- like noise blocker or something right on the PSU casing.

5) OCZ P4 eliminator passive heatsink -- Have a sample, no chance to test, but I doubt it can be run fanless. Fins are to short & don't look optimized for natural convection cooling. Depending on your case airflow, the Zalman 6500B-cu can be, but I prefer a 5V Panaflo instead of no fan: the latter can get tricky & the noise reduction is so miniscule.

The Intel IPC does not allow you to adjust any fan speeds at all. At least not in the current iteration. The speed up/down temp points & the relationship between fan speed & temps are preset, cannot be changed by the user. The fan control is only on 2 case fan headers. The CPU fan header has no fan control, just straight 12V.

The fan on your HS may be thermistor controlled. I do recall seeing in various Intel CPU literature -- can't put my finger on which docs exactly right now -- about thermally controlled fans on HS. I presume Intel HS. I have not examined all the Intel P4 HSF I have for this. Now I will have go and check them all again. Will report what I find.

omigod, I can't believe I never noticed before! The fan that comes with the standard Intel P4 HSF IS thermistor controlled!!

Just took a hair dryer to two different fans from Intel P4 HS, one bought 7 months ago, one about a month ago: the fans speed up fairly dramatically in response to the hot stream of air. My mobo RPM monitoring is not working properly, but I would judge the low-high range to be in excess of 1000 rpm.

This explains what you've been seeing, tywen. The P4 HS roundup review is going to be interesting.

2 options --

1) your favorite quiet fan + http://www.siliconacoustics.com/nmt2.html

2) the Arctic Cooling fan http://store.yahoo.com/svcompucycle/arcoolarfant.html (basically the same one used on ththeir HS -- reviewed here: http://www.silentpcreview.com/goto.php?t=s&id=48&a=1 )