I haven't been able to ascertain the high temp limits of my Haswell I5 NUC. I have asked on this forum and received no reply.
Note the stress test by Bungie. Even he isn't definitive.
>>"The stress testing did however give some fairly high temps:
1 hour Stress Test of CPU:
Max CPU Temp = 82C"<<
I have a NUC with BIOS 18 installed. Intel recommends a "Minimum Duty Cycle setting of 40. At that setting my fan RPM was 3800. I dropped the MDC down to 24 and accepted an idle CPU temp of 46C and fan speed of 1950.
No problems after two months at latest settings.
Until some Boffin and/or smart person comes along your on your own.