Method two is the easier way. It may not reset the RTC clock, but it's fine for everything else that you'd want to "reset" CMOS for - overclocking. That's why we put that switch where it is. The idea of the switch at the rear IO is to make resetting the board easier - it defeats the purpose of having it if you need to resort to taking the panel off the case and moving a jumper. SO I wold not focus too much on the "differences", just use the rear IO switch as it is the most convenient way.

The other methods are more cumbersome simply to clear CMOS.

Maybe a more pertinent question is, what issues do you have with UEFI that make using the rear switch ineffective? 😛

-Raja

@HiVizMan: Interesting, since the button is labeled "Clr CMOS" and F1 is required after it. 🙂

@Raja: I do like the button, but you have to admit that method one is easier (if everything works), 'cos you don't even have to get up off the chair to use it! 😄 No issues here, was just wondering, however, I'd like to use this opportunity to point out a few of my discoveries on and slightly off the topic:

1) in BIOS version 1408 clearing CMOS deletes O.C. Profiles, but in version 1604 they stay there (using methods 1) and 2), didn't test out others)
2) RAID settings seem to be written on the first disk in the array, resetting CMOS does not clear RAID, it has to be done in RAID utility
3) selecting Gamer's OC Profile resets all other BIOS settings, which might be a bug, or a feature 😛
4) on a rare occasion restarting Windows 8 resets some BIOS settings (under BOOT tab, Option ROM Messages goes back to Force BIOS and delay back to 3 seconds).

So, how do I clear O.C. Profiles without reflashing BIOS? And after flashing a newer BIOS, is there a need to load optimized defaults?

I'm pretty much unable to answer your new questions but the reason method 2 is used is if the computer doesn't boot due to a heavily failed OC or if the BIOS are corrupt. Have happened to me some times where the computer wouldn't boot when setting default but would boot after clearing CMOS.

If you flash your BIOS with a new version the BIOS will be set to optimized default.