Hello,
 I mounted a Matsonic SIS 630 133Mhz mainboard with integrated
sound and video system. Pentium III 800.DVDdrive, 2 HD 20 gigs.
LCD flat monitor.
All is working fine except in my sound recording system where a
low frequency (70Hrtz) is adding itself on the view meter.
I also seems to interact with my modem, acting as a ring modulater.
I mounted a separated PCI soundcard. It is better but still there.
There are parasites in the sound.
Of course, I tried all possible adjustments in Windows ME.
Does anyone see the reason for this? 
Mainboard not well grounded? 
Unclean power supply? (I changed that too)
Something not well mounted?
Thank you for any suggestion.
Regards
Joel Vandroo

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