gpu mining – Power Efficiency of rate limited NVidia cards

NVidia is rate limiting some cards to 50% of possible hashrate. What effect does this have on power efficiency?

I can imagine it reducing power efficiency by cutting (same power, but lower hashrate). On the other hand I could imagine it increase power efficiency (but cutting voltage when it detect hashing, halving performance but doubling power efficiency). I haven’t bought a card yet so I cannot test.