Yakfly I put in a lot of powered attic fans as an electrician, but I used turbines on my house. Like F & F said, you want soffit vents, no end gable vents, and enough turbines to get a good timely exchange. On a hot day you can feel the air been drawn through the soffit vents, it's that noticeable.
I assume you can still get with cold weather blocks, but if not it isn't that hard to cover them in cold weather. The thing about soffit vents is that wind won't blow through them, like it will gable vents.