I would think they'd be the first choice for building a silent PC. However, if I had a silent PC, it'd only be running the operating system and accessing files from a server. I've compared music served vs. on-the-pc's hard drive and there was no difference. Not saying there couldn't be. But there wasn't in extensive and laborious back and forth listening. I think you are indeed listening to a buffer from memory, which is a sort-of solid state hard drive anyway.
-C