please check again the temp limit. It is not just the BIOS setting. You need to enable hyper-v in windows. That is the key. Once enabled in windows the machine is locked in with max temp of 80 degrees.
go to lenovo vantage, go to smart settings. diable the function which "smartly" detects the position of x1e, either on a desk or on your lap, and "stupidly" keeping high power consumption even to the simpliest task. then, go to your windows desktop page, go to the taskbar at the bottom, click on the battery icon and drag the setting to the left "best battery life/worse performance". This setting is good/quick enough with all your daily tasks. No more fan turnning on when you use chrome, youtube, word and ppt excel all at the same time.
I have the X1 Extreme i7 UHD now for a few days and the fan noise is really disappointing. Even though I mainly only use browser tabs and a few applications which are idle most of the time, the fans start spinning every +/- minute for a few seconds at a very audible level. This behavior looks to contradict the positive online reviews one can find on the internet about this laptop. One thing I can confirm from those reviews is the rather limited battery lifetime on this UHD version...I don't think the laptop lasts more than 6 to 7 hours on a full charge...
Did you undervolt to perform these new tests? The benchmark seems on par with the non-undervolted version of the i7-8750 on the 1st test. Also, wouldn't undervolting give a better fan performance? Last question, is it possible/recommended to downgrade the BIOS version or there are important updates that shouldn't be passed on with the latest versions?