@wahala:
Not sure whether the chip/core placement is universal, and how that affects compatibility. I wouldn't expect it to work on low profile cards, for example. But at least the mounting gear on the Accelero has two mounting holes per leg. My earlier GPU (nVidia GTS250) used different holes than what the RX460 is using. Not sure if the holes are divided between nVidia and AMD standards, or whether there are more standard sizes, but at least it's compatible with both GPUs I've tried it with.
Also, there were some compatibility issues with the GTS250. The washers/spacers on the Accelero were too thick, and the base didn't make a properly tight contact with the GPU, which resulted in higher temperatures, so had to take the spacers off. After that, everything was ok. Other customers voiced similar experiences.
I think I used the spacers on some other project, so now the RX460 is without the spacers, as well. This brought another problem, as the legs were already slightly bent and conformed during the years (they were in use since 2008 or 2009, I think), which made it possible to tighten the screws too much, which apparently allowed the metal legs to create a shortcut with one of the board's SMD resistors, which was right under one of the legs. As a result, the RX460 wouldn't allow the computer to boot. Not sure whether the resistor placement is standard on every RX460, or whether it was Gigabyte's own design choice. Anyway, once I loosened the screws a bit, it's been working solidly ever since.
Unfortunately, the Accelero is quite old (from 2007), so it might be hard to find. There's Accelero S1 Plus from 2012, which seems like the heftier successor for S1 rev2. There's also S3 from 2015, which is apparently the "upgraded" two-sided version of the S1 serie. There's also the Raijintek Morpheus (from 2014), which is more focused on heavy loads (claims 360W), so it might indeed fare quite well even as a passive cooler. Then again, the fin gaps are quite narrow, so not sure how effective it would be at heat dissipation without an active airflow.
With my RX460, the cooler swap was fairly straight-forward, in itself. Remove card from slot, unscrew and remove the stock cooler, unplug fan connector, clean heat paste residue, apply new paste, plug fan connector/adapter, screw new cooler in, attach fan, insert card back to slot. Took me about 5-10 minutes, apart from figuring out that one of the metal legs was making a shortcut (which I actually already suspected when I was screwing the cooler on the board).
Ps. Keep in mind that it's usually better to keep multiple fans at low speed, instead of one or two fans at high speed. And bigger fans are always better. I currently have one 120mm fan at ~800rpm (CPU), and one 140mm fan at ~0-600rpm (GPU). Dead silent.
Ps2. The cabinet might actually bring more problems than benefits. If it's a closed unit, then the heat will gather inside the cabinet, making the ambient temperature higher, and thus making the fans spin harder.
Ps3. The HDPLEX-250W that LePhuronn linked is indeed an interesting alternative, and should open new possibilities. But IIRC, the problem arose with sourcing a compatible power brick. I don't think it comes with one, and that increases the costs further, not to mention research time.
