ASUS A7V/Thunderbird 1GHz lockup problems observation w/fix for me

Ever since building this system there have been spontaneous and
unpredictable lockups, usually at least once per day. Sometimes several per day. The lockup is sometimes preceded by X starting to display things strangely (on a Voodoo 3 w/XF 4.X). Then I have a few minutes to reboot before it hangs (can't log in using ssh from another system.)
With the Northbridge discussion, I couldn't pinpoint anything to fix it,
so I started experimenting.
Things got better by upgrading the BIOS; but still many hangs. I've discovered that changing the CPU voltage from the default to 1.75V
results in a stable system. Higher than that doesn't work. Lower still gets lockups.
It doesn't look like everyone has this problem with similar setups. But
if there are others, I wanted to share this discovery.