Good Question: No. Power vents are used to remove heat penetration from the attic thru the ceiling in the summer. That way your A/C has to work less. It does not have a real purpose in the winter.
There has got to be more than just hole in the attic.
The objective is to have the attic and the outside at the same temperature.
2 end vents, 1 in each end, is the old-school way. It worked okay.
Continuous venting along the eaves and a continuous ridge vent are today's standard.
That's a much better system.
If you've got an exhaust vent, you've got a "suction" air opening too.
If you are not getting ice dams you're doing fine.
Snow should not melt off of your roof on a cold day.