Never looked at the reviews of the s7 or s9 despite them being several years old now??
The t1 has same layout and lazy/brain-dead heatsink design that makes for them being LOUD due to all of the turbulence created by so many leading/trailing edges on that mass of individual sinks.
ref the
Canaan Avalon repair guide for example of correct thermal design.
That's interesting, since you've mentioned about the S9. I went ahead and found HagssFIN's post on the guide / teardown but the PCB there wasn't visible since I guess the user wanted to retain the warranty seals. I went ahead and look it up on youtube and was amazed to
see that it looks exactly similar to the Halong Mining DragonMint T1, including the outer casing.
Note: I tried googling the Canaan Avalong repair guide since the hyperlink you've provided is incomplete. I came up with
https://bitcointalk.org/index.php?topic=3191702.0 and the technical setup page over here -
https://canaan.io/faqs/avalonminer-721/page/2/ (for the Avalon 741 and 721). What's interesting was as compared to the Halong Mining dragonmint T1, the Avalon 841 has one continuous heatsink without many tiny ones attached to the PCB. Also, the 16nm ASIC chips right beneath them
https://imgur.com/cYXplGP are clearly visible. Looks like an interesting design difference between the two.