Ok i've been investigating a problem here. My pc has degraded over the last month. I.e. Taking more attempts to successfully POST. Now it never POSTS, beeps, displays...
The fans move and there is HDD activity.
However i've played around and found that if i unplug the HDD power, the PSU fan and CPU fan stop moving after a second. With the HDD power cable plugged in the fans resume moving.
I noticed a slight thing with the CPU fan. With the HDD power plugged in. Where the CPU fan would usually stop spinning after a second, i can see it slow down slightly but picks up speed and carry's on due to the HDD being plugged in.
NOTE: I say HDD but the fans will move with any SATA power connector being plugged in.
More about :computer fans move sata power connector plugged read