680x. top radiator push pull

so i had an extra 2 fans lying around, decide to use them for a push pull connfig on my cpu radiator, my question is , the gap between the fans and glass, is it enough for actually exhausting the air out of the radiator ? the improvment in cpu temps is minor, but it is still a difference/

 

The air will get out, but the glass does pose as a measure of resistance and likely decreases airflow compared to if the glass was not there. However, rather than try and calculate some obscure air flow metric, if the temps are slightly better, than slightly more air is getting through. You can weight the performance benefit vs noise cost and decide.

 

Any actual ill effects would be visible through coolant temperature. The worst thing I can think off is the glass retains a heat layer over long duration loads, but obviously if temps are worse than before...

another question, i was told that the pull fan should be a little bit weaker than the push fans, so that they dont fight over the airflow, my push fans are at 1600 rpm whilst my pull fans are at 1300 rpm. is this correct, they arent the same fans , so even at same rpm they will perform differently

Personally I have my pull fans as the higher RPM ones than the push. But it all depends on the airflow of the fans. Either way I think, and this is just a guess, that the pull fans should be higher flow or faster so the air pressure does not build up between the sets of fans.

You want to avoid large differences is speed between fans. Performance difference are not going to be visible. This is more about noise management. Depending on your set up, one side or the other may be louder because of the case material, proximity, etc. if knocking 100 rpm off one side makes sound better, by all means do so. However, if you go to far you are likely to pick up some weird fan harmonics.