4) Another thing I have noticed - both my psus & Kostik's appear the same. But Mike's review pic here
shows a blue wire connected to the immediate right of the fan pin header - we have no wire there at all. Not even a hole in the pcb.
5) And also to the immediate left of the pin header we have a transistor where Mike appears to have a yellow & black wire. It may be Mike had a transistor that is obscured?
Differences 1, 2, 4 & 5 could just be the result of Seasonic reworking the fan control circuit? Would be interesting to know what Mike's 350 & 400W samples are like.
Coming back to the fans and Mike's comments above, I figured I would measure the lowest voltage being fed to my fans. Room temps were about 18C, only load on the psu was a hdd, psu case was open on the floor and the fan was aimed away from the psu. After starting the psu a thermistor balanced on the low voltage heatsink generally rose about 10C which is when I took the 'stable' readings below.
First off I measured my tornado 350W with Yate Loon. Start 4.2V, stabilised at 4.46V after 30 minutes.
Then measured 300FT with SuperRed: the multimeter was all over the place with no reading constant for more than 1/2 second - start fluctuating 4.2-4.5, after 20 mins fluctuating 4.63-4.74.
So figured the FT fan controller could be very different to the 350FB and put the Yate Loon on the FT: start 3.63V, 3.75V after the temps rose. Rock solid (on the multimeter) readings, so concluded the fluctuations with the SuperRed were a feature of the fan itself!
But figured while I was at it would try some other 120mm fans I have on the FT controller (more details on these fans coming in the fan forum later):
NMB - start 6.86V, 6.95V when psu warmed up (5-10 mins)
Papst - start 5.2V, in 10 secs rose to 6.1V and eventually to 6.2V
Evercool - start 3.74V, quickly to 3.8V and stabilsed at 3.83V
Which lead to my conclusion 2 above. But the real gotcha is even swapping fans on these psus is a nightmare as you cannot predict which part of the S2FC curve a particular fan will land on!
One last observation to report - the high voltage heatsink is NOT live - this was tested using a variable speed finger flick until I gained confidence
Anyway, time to get my FB back together and get rid of my 'silent' FSP that was doing temporary duty during testing!