Fan alignment in new build

[Kyle_72]

I just built my new pc. My case nzxt s340 came with 2 fans in it. I believe they are both exhaust fans. One at the top and one in the back. I want to move the fan from the top to the front to get some airflow. https://goo.gl/photos/hy7hwjB57WZKArty7
https://goo.gl/photos/MBKStKQTRjAPoJzL6
Thats how I have the set up. Just want to know if I'm doing this right because I'm a noob.

 

[Zerk2012]

The front fan should be blowing in and the back fan blowing out other than that I would put the front fan in the lower spot to blow on the video card.

 

[raisonjohn]

It's a good start. You NEED an intake fan, so, transferring one of the two included 120mm stock fans from the top to the front will be better (1 intake + 1 exhaust) than just having those two 120mm's as exhaust with no intake fan/s.

However, if I were you, I'd keep the two stock 120mm fans as exhaust and ADD two more 140mm fans as intakes:

PCPartPicker part list / Price breakdown by merchant

Case Fan: be quiet! - Pure Wings 2 61.2 CFM 140mm Fan ($11.79 @ SuperBiiz)
Case Fan: be quiet! - Pure Wings 2 61.2 CFM 140mm Fan ($11.79 @ SuperBiiz)
Total: $23.58
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2017-08-15 13:16 EDT-0400

 

[Kyle_72]

Im in the process of moving the top fan to the front. Im just trying to make sure I have it in the right direction as far as air flow.

 

[Zerk2012]

Depending on the parts used just those 2 fans could be pleanty of cooling.

 

[Kyle_72]

https://pcpartpicker.com/list/G6qQHN
thats the build. when i spin the fan i can feel the air on the outside but not on the inside.

 

[raisonjohn]

Note that the S340 has a solid front panel and takes in the air from the top-front slat

Thus, it's not really known for good airflow (due to the solid front panel), so, it's better to fill up both front intake fan slots with 140mm's (instead of 120mm's) to cover the entire fan slot opening for better air intake (than having a "void")

Here's a nice test video using different fan quantities/configurations in a typical PC case with air cooling and their corresponding temperature readings: https://www.youtube.com/watch?v=8OmkmluAYAQ

0 Case Fans (Air Cooler Only) = CPU: 71C | GPU: 92C
1 Rear (Exhaust) Fan = CPU: 64C | GPU: 85C
1 Top (Exhaust) Fan = CPU: 65C | GPU: 83C
1 Front (Intake) Fan = CPU: 67C | GPU: 80C
1 Front (Intake) Fan + 1 Rear (Exhaust) Fan = CPU: 60C | GPU: 79C
2 Front (Intake) Fans + 1 Rear (Exhaust) Fan = CPU: 58C | GPU: 77C
2 Front (Intake) Fans + 1 Rear (Exhaust) Fan + 1 Top (Exhaust) Fan = CPU: 55C | GPU: 76C
2 Front (Intake) Fans + 1 Rear (Exhaust) Fan + 2 Top (Exhaust) Fans = CPU: 55C | GPU: 76C <-- Adding 1 top fan = no effect as above

 

[Kyle_72]

So I could keep the fan that I have and just purchase another one to throw in the front? Would having them being two different sizes make a difference? Also I have the two case fans plugged into the power supply via molar because my mobo has 4pin and my fans are 3pin. Would plugging a new seperate fan into the mobo cause me any problems?

 

[raisonjohn]

So I could keep the fan that I have and just purchase another one to throw in the front? Would having them being two different sizes make a difference? Also I have the two case fans plugged into the power supply via molar because my mobo has 4pin and my fans are 3pin. Would plugging a new seperate fan into the mobo cause me any problems?

140mm fans usually (not always, depending on the fan design) have better airflow at lower speeds (and sometimes lesser power draw) compared to their 120mm counterpart. The 140mm fan is also logical since your front fan mounting location does support such size. The entire fan diameter will fill up the whole front holes of the frame, and as such, would have better airflow, taking in outside air and directing it into the interior of your chassis.

Plugging fans directly to the PSU via molex will make such fans spin 100% (full speed / noisy) 24/7 without any control and/or monitoring. Thus, it's better to use your motherboard's available fan headers for complete control and monitoring of your rpm (fan speed).

Your Gigabyte AB350 Gaming 3 has a grand total of 5 fan headers (all 4-pin), including the CPU_Fan Header. All the 4-pin headers of your motherboard support PWM control (for 4-pin PWM fans) or Voltage/DC control (for 3-pin DC fans). You can set this in your BIOS.

Simply plug the 3-pin fan connectors on the 4-pin fan header by aligning the tab that encompasses pins #1, #2, and #3, to the fan connector groove like this:

Setting the 4-pin header to Voltage Control Mode in BIOS will allow your 3-pin fans to change speed by varying the voltage supplied. Note that if you set the header in PWM Control Mode, the 3-pin fans will run full speed 24/7 (similar to plugging them in the PSU). So make sure to change the control mode in BIOS if you don't want fans spinning 100% (noisy).

Note also that if you run out of fan headers for additional fans, you also have the option to get a 2-way fan splitter such as these:
For 3-pin fans: https://www.amazon.com/Splitter-Extension-Sleeving-Connectors-Length/dp/B00C46DX4S
For 4-pin fans: https://www.amazon.com/SilverStone-Technology-Sleeved-Splitter-CPF01/dp/B00B46XKKQ

The above splitters will allow you to plug in two fans using just a single fan header of your motherboard.