Everything is connected to the psu as far as I can tell.
fan 2 seems to be the one that never goes below 55 even at idle but I cannot tell which fan is which.
If your fans are connected directly to the psu then they wont read out their speed into your computer, so they should all say 0 in speedfan.
Fan 2 looks like your north-bridge, since its a small high rpm fan, 52C isn't that abnormal for your north-bridge to run at.
Your psu fan will not read out its speen into your computer as well. I look around, it looks like Corsair added a semi-fanless mode to its PSU's, so it will only run if it needs to. So it should be pretty normal for the fan on your PSU not to run.
It it still isn't running during game usage, its likely that your ambient temps are low enough, or you are just getting enough natural airflow through your psu that it doesn't need to run.
Like I said, generally you should only be concerned about damage occurring if you are seeing temps over 90C, that's when most of your hardware's safety settings are at.
Seems to me like everything on your computer is operating as it should.