Could be casting flaws on the fan as well since it's only a few degrees. Maybe check for burs or casting marks on the new fan, maybe it's not as refined as the old one?

Also the gaps around the fan/shroud play a part in the cooling efficiency of the fan too, make sure it's properly spaced out like the original fan was.

Could also be resistance or voltage drop, not seeing full voltage = not running at full speed?

Those are just the things that come to the top of my head, I couldn't tell you if any of them are the problem, but if it's a quality piece those issues come to mind.

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- 2001 X5 3.0i Titanium Silver -