I remember a release note about the card behing halved like this... flashcache was not supported 8.1 but pamii still was from what I recall.. I can't find the doc or engineering update though but do remember seeing this before.
Data ONTAP 8.0.4 & 8.1.2 and later contain improvements which are expected
to reduce the severity of the memory contention.
In case of FAS3140 storage controller, Data ONTAP 8.1.2 and later would
reduce Flash Cache usage by 50% to avoid over memory subscription.