Lian Li PC-B25S Mid-tower Aluminum Case

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TESTING

The same system used in many of our ATX case reviews was used again, for consistency.

System Configuration:

Measurement and Analysis Tools

  • CPUBurn processor stress software.
  • FurMark stability test to stress the integrated GPU.
  • GPU-Z to monitor GPU temperatures and fan speed.
  • SpeedFan to monitor system temperatures and fan speeds.
  • Seasonic Power Angel AC power meter, used to measure the power consumption of the system.

System temperatures and noise levels were recorded with SpeedFan and GPU-Z at idle and on load using 4 instances of CPUBurn to stress the CPU, and FurMark with the Xtreme Burn option to stress the GPU.

FANS

Lian Li has its brand on the fans in this case, but we know the company is not the manufacturer, which could be any one of the many DC fan makers in China. The basic geometry and design of the fans is decent. The four struts on both 120mm and 140mm fans have decent geometry and low profile for low noise potential. The 120x25mm is a moderately swept back 7-blade design, and the plastic does not exhibit excessive brittleness which can lead to vibration induced resonance. The 140x25mm top fan is a similar 9-blade design. Both use ball bearings. The accuracy of the specifications provided below is questionable. Lian Li does not provide full details, and much of the data was found on retailer sites. Since these fans are not effectively marketed or distributed, no serious effort was made to assess them individually; we focused on their overall cooling and acoustics performance in the context of this case, especially in unison with the built-in fan controller.


Back panel 120x25mm exhaust fan. The two in front are the same.
120 mm Stock Fan Specifications
Brand
Lian Li
Power Rating
3.24 W
Model Number
LI121225BL-4
Airflow Rating
56 CFM
Bearing Type
Ball
RPM Rating
1500 RPM
Corners
closed
Noise Rating
24.7 dBA
Frame Size
120 x 120 x 25 mm
Header Type
3-pin

Three of these 7-blade 120x25mm fans are provided in the Lian Li PC-B25S — two in front and one in back. Using the built-in fan controller settings, we listened to them and measured RPM as well as SPL while they were mounted on the case as shipped. There were no significant differences among them. The measured data is provided on the table below.

Subjectively, the 120mm fan was objectionably noisy at the maximum speed. Even at medium, it had a humming quality that was easily heard, especially if more than one of the fans was running. Only at the low setting could be judged as being smooth and quiet enough.


Top panel 140x25mm exhaust fan, with 3-position switch off one side.
140 mm Fan Specifications
Label
Lian Li
Power Rating
2.88W (Max)
Model Number
LI121425BE-4-A or CF-1410B
Airflow Rating
73 CFM
Bearing Type
Ball
RPM Rating
1000 RPM
Corners
Closed
Noise Rating
26.95 dBA
Frame Size
140 x 140 x 25 mm
Header Type
3-pin

The 140x25mm top fan has 11 blades instead of the 7 in the 120mm fans. Despite the 2 dBA higher noise spec, it sounds quieter and smoother than the 120mm fans at every speed setting. At full speed, it is not quiet, but it is smooth enough not to be too obtrusive. At medium, it is not too bad, and at low, it is quiet and smooth enough for most quiet-obsessed users.

Lian Li PC-B25S Stock Fan Measurements
Fan
Low
Med
High
RPM
SPL
RPM
SPL
RPM
SPL
140mm
640
15
750
19
970
26
120mm
830
16
1000
20
1280
28
Fans measured w/o grill or filter, in dBA, from 1m distance at 45° angle.

In summary, neither of the stock fans compare well with the established quiet leaders (Nexus and Scythe 120mm fans, particularly) but they are quiet enough at the low setting. With the case all closed up, and with the baffle over the top fan, they are much quieter in actual use than the above measurements suggest.

BASELINE NOISE

Noise measurements were made of the case with the rear, front and top fans at low, medium, and high settings of the fan controller. Only one of the two front fans was connected, as the second one seems superfluous for cooling the test system... and because the fan controller has only three headers. The side mounted HDD drive cage impedes airflow enough that the front fans' cooling effectiveness applies only to the drives; little of the flow from the front fans can be felt at the front edge of the motherboard, even when the fans are run at high speed. All the grills over the fans were removed; only the front fan filter was left on — this resulted in a 1-2 dBA drop in noise compared to all filters and grills on. The top baffle as well as the front bezel were left on.

The air cavity resonances inside a case amplify fan noise, as do any vibrations transferred from the fans into the case, so these measurements can be regarded as the baseline or minimum SPL levels for the case and stock fans.

BASELINE NOISE
Speed
SPL@1m
Rear
(120 mm)
Top
(140 mm)
Front
(120 mm)
LOW
off
15 dBA
off
LOW
off
14 dBA
off
LOW
16 dBA
LOW
off
17 dBA
off
LOW
17 dBA
LOW
18 dBA
MID
off
20 dBA
HIGH
off
26 dBA
MID
22 dBA
HIGH
28 dBA
Measuring mic 1m at 45° angle left/front, roughly 1' above top of case. Note: Adding the second front fan (using a splitter with the other front fan) increased SPL by 2 dBA on average. Subjewctively, it seems louder than that.

It is easy to see that all fans on LOW is a sweet spot for noise and airflow. Adding a front fan to the back and top fans on LOW makes no change to measured (or heard) noise, so it pays to keep it on. With three fans on MID, the noise level jumps 4 dBA; keeping the front fan off helps quite a bit, and at that speed, the back and top fans are pulling enough air through the front panel that the HDDs would get decent cooling anyway. The HIGH position is unacceptable to most silent PC enthusiasts, although many gamers would probably find it acceptable.


Optimum baseline noise with 3 fans on low measured 18 dBA@1m.



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