This drive is almost certainly (~80% sure) a rebranded LiteOn drive, which means it's a rebranded Optiarc drive. Here's some added validation:http://club.myce.com/f43/plextor-px-l890sa-316174/
"So what?" These drives appear to use ball bearing mechanisms, which makes them extremely loud during spin-up, spin-down, and idling. They're fast, yes, but loud. If you take the drive in your hand and turn it or rotate it and you hear a "hissing", it uses bearings -- what you're hearing are the metal bearing spinning around a metal track. If you have sensitive ears, you absolutely will hear this during normal use.
I just completed a review of the LiteOn iHAS424-98 (which is a rebranded Optiarc) over on Amazon, in which I stated I'm returning said drive because of the bearing noise. Sony introduced this crap back in the mid-to-late 90s and I'm absolutely amazed people are still using it. I love my Pioneer DVR-212DBK (quiet!), if only it could read some of my audio CDs and had better error handling (for minor scratches) on DVD movies.
All the drive re-branding going on these days (LiteOn selling rebranded Sony Optiarc drives, Plextor selling rebranded LiteOn drives (and before that, rebranded Pioneer drives), Asus selling rebranded LiteOn drives, etc.) is really sad. Remember when Plextor made their own stuff and it was awesome, plus quiet? Yeah. :-(