Changing and adding case fans? With picture and full description

SPECS

Case: Antec P280
Motherboard: ASRock Z97 Extreme6
PSU: Super Flower Leadex Gold 650 W
CPU: Intel Xeon E3-1230v3
GPU: MSI GeForce GTX 970 Gaming 4G
CPU Cooler: Scythe Mugen 4
RAM: 16 GB Crucial Ballistix Sport 1600 CL9
Drives: 2*SSD, 2*HD, 1*BD Burner


MY GOAL

The system should be more quiet while on low load action, like reading in web
browser and when no music or other sound is playing. I am thinking of replacing
outer case fans for less noise and adding internal case fans for helping to
cool hd drives, gpu and psu a little, while beeing silent. On low load situation
currently only the case fans are a little too loud to me. The whole system is
still almost silent, but that is something which can be done better. I am
concentrating to case fans now.

These are the alternatives I thought about, just some ideas:

be quiet! Silent Wings 2 PWM 120mm
1500 rpm, 85.8 m³/h, 1.63mm H₂O, 15.7 dBA, 4-14v, 2.4 W, 4-pin
I don't know if I can use the vibration absorber or whats called.
http://geizhals.de/be-quiet-silent-wings-2-120mm-bl062-a745182.html?hloc=at&hloc=de

Noiseblocker NB-eLoop B12-1
800 rpm, 57.3 m³/h, 0.58mm H₂O, 7.8 dBA, 3.9-13.8V, 0.33 W, 3-pin
Is this strong enough? I think only the cpu side is needed to be cooled.
http://geizhals.de/noiseblocker-nb-eloop-b12-1-itr-b12-1-a820044.html?hloc=at&hloc=de

What do you think would be the best for my case? I just don't know.


DESCRIPTION

1) Case fans
The 3 case fans are taking the warm air from cpu out. They are controlled by
case and have two speed modes: fast and slow. I use them generally on slow mode,
because its not that loud and the performance is enough even if I benchmark at
hot summer days. The manual says:

120 mm TwoCool specification
120 * 120 * 25 mm
12v DC
Low setting: 900 rpm, 0.18 A, 0.84 m³/min (30.1 cfm), 0.49 mm-H²O, 16.9 dBA, 2.2 W
High setting: 1500 rpm, 0.30 A, 1.43 m³/min (51.2 cfm), 1.21 mm-H²O, 27.9 dBA, 3.6 W

2) CPU cooler
The big tower could do the work without the installed fan I think. The fan on
the right side takes the air and pressures through the cooler to the other side,
which will be handled by case fan afterwards. The setting is set on bios to low
speed, which is around 600-700 rpm. This is the default for me and it is enough
in all cases. Its already almost inaudible. Only if I change to next step up to
over 1000 rpm or more (I did not any note on that), it gets audible noise. I
just don't need that setting. I think, I can leave this as it is.

3) GPU
The graphics card have its own solution. The surroundings does not heat it up.
The fans are set to off, if on low load. At high load or if it is hot inside,
the fans are starting to spin. It works great. I do not overclock and on high
load it does not exceed 71° (if I'm not mistaken). Currently on low load (while
writing this) it is 40° hot and fans are stopped.

4) PSU
Like the GPU, this unit have its own solution and there is nothing surrounding
which would heat it up. The unit is very silent on low load operation and at
high load, I don't know. This is absolutely no issue, no heat and no noise
issue.

5) Additional Case fans
This is one place where I could put two additional case fans to support gpu,
psu and the hard drives. The cables on are not in the way, just a little. The
hard drives are not used much. Most of the time the ssds on top are used (os is
installed on ssd). I think the temperature of the hd and ssd is no issue here.