My case is a Zalman Z9 Plus and the side panel supports up to 2 140mm fans.
I found this adapter that allows me to put a 200mm fan in a spot for 120mm/140mm fans and am planning on buying 2 and putting 2 200mm fans in the inside of my case for optimal cooling and silence
I was wondering before i buy these if they will be too big, or not fit, and any other concerns I might take into consideration
I have that case and it's great. I really must say that that adapter looks like it will only get in the way. Tell me everything else you're using inside the case so I can better advise.
The lower fan on the side panel sits right over your gpu. It would probably touch my gpu (sapphire 6950) or stop the side panel from going on.
The upper side fan sits over the area to the right of your cpu cooler. I have a hyper 212 evo plus which I had to mount exhausting out the back of the case just to get a 120mm fan (which was 25mm deep) in the case. If I didn't I had to take the top side fan off.
Come to mention it you say the side fans are 140mm but they are 120mm. I can give you a few tips on setup if you let me know the rest of your build. My rig is almost silent. The Mrs will allow it in our lounge and that is saying something.