Yes. That was my comment. There are kind of magical numbers for coolers. Here they are:I forget: would the flex slot/3-slot card design still accommodate 2.5" drives? I currently am making good use of spots on the S401, maybe wouldn't use them in a future build, so I'm not advocating one way or the other, just curious about their status.
This isn't an original thought but I can't remember where I first saw it (credit where credit is due). Someone once pointed out that there are a few "classes" of air cooler height (and I know there are way more coolers than I can think of on the fly here; these are just a smattering of popular ones). Up to around 40mm covers Intel stock cooler, Noctua NH-L9, and Wraith Stealth (I think?). Up to 50mm covers C7 and Black Ridge (and similar). Not too many coolers come into play at 60mm except the Big Shuriken 2. Then, at 70-80mm, we start getting the Noctua NH-L12 class coolers. So, a proposed cooler height of 59mm is good but still locks down from the highest end down-draft coolers (which is fine - this is just an observation). I would be able to go back to my old RVZ02 configuration of C7 heatsink with NF-A9 (25mm thickness) if memory serves correctly. That could be an effective combo for the proposed S402 width/cooler height.
Thinking of the RVZ02 again reminds me it can only support a 2-slot card and had about the same amount of usable cooler height. I think someone here already established it would be smaller than the Node 202 as well (and much breezier). On a different sort of scale, you could probably knock out both of those cases: smaller than both, matching or better component support (with the proposed 3-slot design), and better ventilation.
I wonder if 3-slot support would also help clarify the difference between the S402 and the Sentry 2.0. I'm cautious here since I don't want to come off as a Sentry-bashing Salvo fan. I am a Salvo fan but I am also extremely pleased to see the dent in mindshare that Sentry has accomplished with respect to premium SFF cases. This is why I think a clarifying difference is helpful - both cases can succeed in their own ways. At present, the S401 has similar component support to the Sentry 2.0 while being slightly larger in most dimensions (correct me if I'm wrong). I think S401 can fit more 2.5" drives and I anticipate the horizontal config is slightly more efficient with air coolers. However, primary component support is similar (~50mm coolers and 2-slot video cards). The S402 will still exist in the same sort of market space. 3-slot support and increased CPU cooler support may increase the S402's desirability when considered in a wider context.
Still, at the end of the day, that number followed by the big L is an absolute measurement. Personally, I come down more on the side of the 3-slot cooler design and resulting increased width. Of course, it will be helpful to see those renders comparing existing S401 dimensions.
Finally, congrats on the sale of the i9 S401 build. I hope it goes to a good home.
Up to 40mm. This is about up to where the top of the IO cover sits. AR05, NH-L9, ITX30, IS-40.
Up to 48mm. This is based on intel stock cooler specs. C7, Black ridge, AXP-100 a couple unknown ones.
Up to 60mm. This is pretty much the smallest size for 120mm coolers that sits over the RAM. Big Shuriken 2b, Samuel 17, REEVEN Brontes, IS-50/60, AR06, AXP-200, Deepcool Grabiel.
And above that is pretty varied.
60mm is the sweet spot in my opinion. It gives a few decent choices and that is when the cooler can use 120mm fans. It is where your choices really open up. 55mm is a weird spot cause you can't use the 120mm coolers.