That configuration might actually work nicely. Everything is coming in all sides but one, which is the exhaust. Just make sure to filter all intakes as best you can. If you can't find a suitable filter for the side fan, I would consider not using it, making the two top fans intakes, and the radiator an exhaust.
If you want to know why I'm leaning more on more intake than exhaust...
- This creates more air pressure in the case than outside. This means every tiny hole in the case will blow out. This prevents dust from getting in. The opposite effect, while it draws in cool air from every hole, it also draws in more dust.
- Because there's less dust able to get in, your case is effectively like a clean room. You'll find your parts less dusty over time. The only thing you have to remember is give the filters a cleaning once a month
- Also because all the holes in the case are blowing out, there's no chance exhaust gasses can be inadvertently sucked back in.
- Because there's more relative air volume in the case, you potentially have more air to work with.
I used to be concerned about airflow, but then I realized: parts that need airflow have something called a fan. The airflow produced by the fan is orders of magnitude higher than any natural airflow in the case.