On the 1800x which is 4.0 stock and has a TDP dependent boost to 4.1 also stock?That doesn't seem very high to be honest but it's still early days, I'd expect max clocks for most folk on standard cooling to be at least a full ghz lower than that.
Seems unlikely to the point of crazy that it would then fail to go above 4.2 with ambient cooling and actual effort put into overclocking it.