Do BIOSes change memory settings automatically?

Recommended by Wim's BIOS...

Sometimes when my computer won't boot with a certain type of DIMM (blank screen or long beeps), if I keep trying to reboot by hitting the reset buton, the computer will eventually boot, and from then on it boots on the first attempt, even if unplugged and the CMOS battery removed. Does that meant that the BIOS tries different settings each time a boot is unsuccessful and stores them in the BIOS chip? It doesn't seem to reset the BIOS to the default settings because I can still see the faster memory timings chosen. By the way, I'm referring to when automatic DIMM settings aren't used.

[soupy]

Sounds like you're trying to run a CAS3 DIMM at CAS2?

This CAS3 PC133 DIMM works fine at CAS2 and 100 MHz, but all I get is a blank screen and maybe long beeps if I use CAS3. Almost all my problems have been with VIA mobos, but one DIMM didn't work in my Intel 440BX without some tweaking. OTOH an old Intel 430TX board I have doesn't care what memory I plug into it or what BIOS settings I use.