TRYING to understand the broken English used here so forgive me if i misunderstand what the OP is saying. so i'm just going to speculate on what it is we are trying to give advise on.
a quick google indicates the chassis is this? is this correct?
if it is correct, then these are the supported venting options
System Fan (mm) Support
Front: 120/92/80 mm x 1
Rear: 120/92/80 mm x 1
the OP has at "maximum" a 120mm front intake and 120mm rear exhaust.
here is a pic of the rear exhaust option
here is the dimensions of the chassis
Dimension w/Bezel (W x H x D)
180 (W) x 408 (H) x 430 (D) mm
we can safely conclude that the supported HSF height is at or less the 160mm
with these facts, we are forced to agree with doyll's analysis of needing a new chassis if the goal is going to be anywhere near "quiet" since there is simply not enough intake fan area for "quiet" operations
the OP also indicated the primary suspect for offending noise level originates from the GPU. here is a pic of the GPU in question (brand is not indicated so i just grabbed a random pic from google, but since it's a budget GPU, most of the cooling solution are not going to be significantly better then this pic)
there isn't going to be anything significant we can recommend here since ANY solution on the market is likely going to cost more then what the GPU is worth at this point
so... we are left with the giant question that everyone is avoiding up to now.... just how much is the OP willing to invest in his current system or is he going to be better off saving up for a new build?
the best recommendation right now is a gradual upgrade path which may have little to do with the stated goal of this post but he will eventually upgrade to the point that the system becomes quiet. i would definitely start with a new chassis which will allow him to fit larger HSF and PSU. then the path of going quiet is at least open.
the alternative path is of course the investment in a dremel
but i'm not sure how comfortable the OP is with THAT idea