Slipped by me last night. My clock is also affected by this. I need to update the time constantly to keep my clock correct. During a day's use, the clock may end up 10 minutes wrong or more. This is irrelevant to setting the timer to acpihpet0 or not. Just reading my email has my clock wrong by about 3 minutes. I set it to the correct time in the BIOS right before booting.
Since I mentioned the BIOS just now, I need to check to see if there is a newer one. It's possible that there is not a flaw in OpenBSD, but a flaw in the current BIOS version I have. I have found it a little puzzling why no one else is complaining about this problem. Thanks, Chris Bennett