has some other details but I'm on a different HS and fan now so my speedfan settings have changed.
The stock AMD heasink had a 70mm fan that 29% in speedfan gave me 690RPM and 85% gave me 2800RPM, I'm not sure what 100% was but it was over 3000 I guess.
The Tranquillo stock fan was PWM and whether it was the motherboard fan control circuit or the fan I couldn't get anything less than 670RPM out of the Tranquillo PWM fan. At 100% speed it was over 1400 RPM. After playing with it I decided the PWM range that made sense was 35% min and 73% max. At 73% the fan noise was noticeable but not as obnoxious as the 1400RPM level. I didn't write down the RPM at 73% but 35% got me that 670 RPM I mentioned.
I took that fan out and put a Yate Loon D12SL-12 3 pin fan in and was able to get speed fan to control the Yate Loon to 0%, and from 20 to 100%. 20% on this fan was around 340 RPM. The fan won't start at 20% so if I allow it to stop it takes a much higher percentage to start. To avoid that lag I decided to run with speedfan set to 20% minimum and 100% maximum. fwiw the Yate Loon at 100% is over 1400 RPM as well but is much quieter than the Tranquillo. In fact I'd rather have the Yate Loon at 1400 RPM than the Tranquillo at 73%.
Also because the Yate Loon is so smooth sounding I've changed my mind about the Delta value % in the speedfan options. I used to think (from lack of experience) that a 120mm fan would need a lower percentage than the 70mm fan. I was running on 3% with the AMD stock HS/Fan, I've moved it up to 5% on the 120mm yate loon and I might be willing to run it at a higher percentage.
I ran 3D mark06 last night and all though the speedfan graph shows me the fan varied from 300 to 700 RPM during the benchmark I never noticed the noise change at 4%. I'm thinking with this HS/Fan combo that even 10% might be reasonable but I'm too impatient to bother running the bechmarks enough times to find out.
The big advantage to a higher percentage Delta is that during boot my system ramps the CPU fan to 100% and when speedfan loads it starts to slow the fan down. A higher Delta % means less time until the system gets down to the under 400RPM range where it'll sit most of the time.
I could use a lower maximum like say 75% to shorten the trip on the way down but it's so smooth sounding I figure I'm better off just leaving the full range there for speed fan to use if I ever play a game that truly heats things up.
Maybe if I ever get the last hard drive out of the case when SSDs are cheaper I'll change my mind and throttle that fan down some more but for now I'm happy with how it works.