For those who are interested in this Thecus but want much lower noise, the obvious steps are to slow down the case fans (either by replacing them or a simple in-line resistor like the ones supplied with all Noctua heatsinks), the CPU cooling fan (online resistor is probably best), and the PSU fan. The last does require swapping out the fan in the PSU, which is not recommended unless you have experience and/or are very handy. The alternative to swap out the PSU for a quieter one. A reasonable bet is the Seasonic 80+ Bronze 250W 1U/FlexATX -- http://www.seasonicusa.com/PDF/Catalog/ ... ve-PFC.pdf
They claim 25 dBA@1m at full load, which suggests that at much lower load (like the <100W loads here), it will be <20 dBA.
Another forum member recently did a swap (in a different system w/ noisy PSU) with a similar 1U Seasonic, with good results: viewtopic.php?f=6&t=67975&p=589237#p589237
Of course, this kind of modding will likely invalidate your warranty. Do keep in mind that no matter what fan mods you do, 7 of even the quietest, lowest-vibration HDDs will produce at least ~18 dBA@1m.