Yeah, sure thing, I understand that. My logic was that:
1. When compared directly using the same cooler, the highest clocked Ryzens are cooler than the 7700k, with the 1800X hitting 65C against 7700K's 74C, and 1700X being some 20% cooler here: http://www.tomshardware.com/reviews/amd-ryzen-7-1700x-review,4987-8.html
2. The stock 7700k was said to be kept at 70-80-ish C by the NH-L9i, with the highest any review got being 92C during a stress test http://www.funkykit.com/wp-content/uploads/2016/08/NF9i_res1.jpg
3. I believe throttling for Zen kicks in at 75C (AMD claims 95C but the offset makes it confusing). Therefore the lower clocked Ryzen chips might do completely fine with that heatsink as they are significantly cooler than the 1800X, which is cooler than the 7700k. Going by those calculations of the 1700X being 20% cooler than the 7700k (IRL probably more if counted over ambient) all things equal and extrapolating those results, even the 1700X would max out at ~73C on that cooler. The 1600 and 1700, for instance, run significantly cooler than the 1700X so a ballpark estimation is they'd be completely safe. 1700X could be pushing it under sustained load if you factor in higher ambient temps, inferior airflow, unlucky silicon etc.
It's just my speculation at this point as I'm not sure if anyone had a reason to test Ryzen with low profile coolers yet apart from the Wraith Stealth, which is taller.
I just found this, however, which is I guess the best thing for estimating cooler clearance for the Biostar ITX board at the moment:
http://www.biostar.com.tw/app/en/mb/introduction.php?S_ID=878#specification
"Cooler Installation Notice :
AMD Wraith Stealth CPU cooler only compatible with DDR4 modules without heatsink(The depth of memory within 45-70mm can be installed, but it may touch the cooler.)
AMD Wraith Spire CPU cooler compatible with most DDR4 modules with heastink(86mm)
AMD Wraith Max CPU cooler only compatible with DDR4 modules without heatsink(The depth of memory within 45-70mm can be installed, but it may touch the cooler.)"
No info regarding messing with the VRMs, but the L9a is just 5mm wider than the Spire and smaller in all other dimensions so it should be ok I guess? (Biostar suggests that depth is the problem, as width of all 3 AMD coolers is the same).
http://noctua.at/en/nh-l9a/specification
http://cdn.wccftech.com/wp-content/uploads/2017/02/AMD-Ryzen-1800x-1700x-1700-boxes-coolers.jpg (wrong height, does not include fan)
