Here’s an excerpt from Reuben Saltzmanhttps://structuretech.com/roof-vents-problems-and-solutions-2/in his article:
MIXED EXHAUST VENTS
For proper ventilation, both high and low vents should be installed. On paper, high vents are supposed to act as exhaust vents while low vents should act as intake vents. Convection is supposed to help make this happen. In reality, it all depends on how the wind blows, convection has little to no effect, and it’s never perfect. The intake vents will typically be soffit vents, while the exhaust vents may consist of ridge vents, turbine vents, box vents, or powered vents… but only one of those.
Power vents shouldn’t be used because they create more problems than they fix. You can find more about them in this blog post: Attic Fans Won’t Fix Ice Dams (or anything else).
CROOKED TURBINE VENTS
The important thing about turbine vents is that they need to be installed perfectly level; when they’re not installed level, they don’t turn.