Okay, you seem to want detailed data, TheLab testing do not have 250 watts, but have 232 watts heat being 5.5c and 289.9w is 7.0c heat ..345 watts is 8.3c and 117 watts is 3.7c. That is a lot closer to my '5-8c' then your 'shoyld be 4c' is.
Different cooler orientation makes less then 2c difference in temps.
But it's a mute point because while NH-U14S should fit on G1.Sniper M5 with GPU is in middle PCIe x16 socket. But I don't think the U14S at 165mm tall will not fit in the 350 case which I think only has 160mm CPU clearance.
If you want the best cooling and lowest noise level the Thermalright Le Grand Macho is 159mm tall, 70mm center CPU toward PCIe (near side of closest x16 PCIe is 73mm from center CPU) and cools as quietly or quieter with as good or cooler temps as NH-D15.Edited by doyll - 11/12/17 at 7:04am