If this was a reply to me then you might have got the wrong idea, the power controls for hard drives are adjusted through windows (control panel-power options), it doesn't really relate to which PSU you are using, its a feature designed to save power/reduce heat when the drive is not in use, but if the time is set to something lower than 5 minutes then it can trigger far more often than you want producing the lag and odd sound looping while the computer is waiting for the drive to become accessible again.
It's only a guess though, this could be nothing to do with it, but I have had similar problems to what you explained previously with write caching disabled and the power settings set too low.
For the write caching options, you need to open the device manager (control panel->device manager), expand the disk drives section, double click each drive and then look in the Policies tab, you want the first tick box enabled (write caching), but leave the second box unticked (turn off write cache flushing) as turning this option on can make any random crashes cause a lot more corruption.
If the write cache options are grayed out and unticked then you might need to replace whatever sata drivers you are using for your motherboard.
