[ index ]
The replacement of the chassis knobs/feet's. :
I removed the crappy plastic knobs from the chassis, and replaced them with
shock-absorbing rubber-feet's found on an old refrigerator compressor. I was really lucky
here. The mounting kits and everything just clicked right inn.
The construction of the noise box for the hard-drive :
- details to come. further and more targeted insulation. [ work-file ]
An elaboration of the different prototypes of noise traps.
Testing the system under different CPU clocking/voltage settings.
Note (1) MB clock multiplier set at 1.5 (that is 3.5 for P233-MMX) in all measurements.
Note (2) CPU Fan present on prcessor all the time, even when dissabled. This might have an effect on the air-circulation over the cooling rib. May improve some if removed.
Note (3) : The utillity "CPU Stability Test" v6.0 was used for stabillity testing.
Summary : Experimanting with the different settings, showed that the HF PSU noise did change with different settings. I didn't systematically test and record this, but a major improvement was noticed when going from 3.2 Vcore to 2.8 Vcore. The sound was never eliminated permanently at anypoint however. Furthermore the lower power-consumption reduced the PSU cooler fan speed and noise some.
Update on the Hi-Frequency PSU Noise problem.
Searching the net I found a document [ ref.1 ] by Samuel M. Goldwasse, which suggest that the noise stems from the high frequncy coils and capacitors used in the PSU. Based on this information it should be possible to do something about it.
Testing of the Waterfall software cooling utility. (vs. CPU Idle).
All of them worked great. No preferences. Although the shareware edition of CPUIdle (v 5.6) had a more convenient system load meter (LED-like in the sys-tray).
Adding of a separate power-line with switch for the CD-ROM / Floppy drive.
Notes ! Switching power on or off while system is running, may cause som instability. Possibly due to some power-surges or noises, I don't know. I just observerd it. Could add some filter on the swithch in the future to try to solve this minor problem. For the time beeing, I just decide at boot-up wheter I need the devices on that line. And if I find out that I need them when system is running, I take head for that the system migth crash if switched one way or the other.
Creating a tool for locating the noise sources.
Mounted a small plastic tube on a microphone and wrapped the whole thing up with clingfoil and cello-tape. Hope it works.
Other stuff :
Additional attempt and remedies for noise reduction, based on the new information.
Update - The problem with the monitor (as from now refered to as monitor 1) was solved by itself. After anoying me for approximate 2 years, the monitor terminated said good by with a sudden flash. Only a flat horisontal line wisible on the screen. Sendt for repair. Downgraded from 17 " to a 15 " which feels like heaven. See system specefications for details. monitor(2).
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