atacontrol not reflecting disabled write cache (or rogue hdd?)

I've recently changed hw.ata.wc to 0 (via loader.conf.local) on two systems 
and on both systems atacontrol cap still says write cache supported & enabled 
(sysctl confirms the setting being 0). One system is 5.0-RELEASE, the other 
4.8-RC.

Is atacontrol lying or do the drives insist on write caching?

The drives are SAMSUNG SV4002H and SAMSUNG SV8004H/QR100-12.

-- 
Regards,
	Michael Nottebrock