You can read SPCR's review of the S-Flex fans
and the stock Scythe fan
The Ninja-Plus fan is the Scythe model 62027, AD1212DS-A73GL(6TCL3). At 1028RPM, it is exactly as loud and sounds exactly the same as the Scythe S-Flex E.
A comparison from a (once?)
well known board member.
These are a few years old, but were in excellent condition when I used them last. And they're whisper quiet at full speed. $15 shipped
(for all four, us48)SOLD
[url=heatware.com/eval.php?=66368]H E A T W A R E[/url]
Heatware is down again, so here's a text only web copy