Cooler Master Silencio 652S Tower Case

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The Silencio 652S is Cooler Master’s latest take on the modern silent tower. It has the look of a quiet case combined with the versatility of a well-rounded model.

March 30, 2015 by Lawrence Lee

Product
Cooler Master Silencio 652S
 ATX Tower Case
Manufacturer
Price
US$110

Cooler Master is best known for their enthusiast class cases but they have
a history of producing silent-oriented enclosures as well. Over the years we’ve
examined a few offerings from their Sileo and Silencio series, which have had
a more refined low-noise oriented design compared to their other offerings.
Quiet cases usually trade some airflow for greater noise reduction, but with
a well-designed chassis, it’s certainly possible to deliver both, especially
for a manufacturer with this much experience.


The box.


The Silencio 652S.

The Silencio 652S is the most upscale quiet case from Cooler Master so far.
Its appearance jibes with most SPCR enthusiasts: An understated boxy tower with
a steel/plastic construction and a matte black finish. However, hidden behind
solid panels are numerous fan options, including a massive 200 mm placement
on the side panel that would be perfect for cooling down a graphics card, and
removable dust filters service every location. A door at the front helps block
out noise from intake fans while ample slits running down the sides of the bezel
look good for fresh air intake.

On the inside, the side panels are lined with foam, and three of the fan vents
are occupied by Cooler Master Silencio
FP 120 fans, also billed as silent. For enthusiasts, radiators up to 240
mm can be installed, as can CPU heatsinks up to 16.8 cm in height and video
cards up to 42.3 cm in length. Drive support is strong with a maximum of 10
x 2.5-inch drives or 9 x 3.5-inch drives (or a combination of both). Along with
front USB 3.0, Cooler Master throws in a rare addition in the form of an SD
card reader.


Accessories.

Included in the accessory box is a set of 5.25 to 3.5-inch drive adapter brackets,
zip-ties, a short assembly guide, a PC speaker, anti-vibration pads for mounting
2.5-inch drives, and a mysterious long standoff for the hard drive cage that
gets no mention in the manual. All the screws and standoffs are jammed together
in a small bag even though though there 10 different types of screws inside
meant for different applications; it would have been nice to have these sorted
and separated.

Specifications: Cooler Master Silencio 652S
(from the
product web page)
Model Number SIL-652-KKN2
Available Color Midnight Black
Materials Polymer, Steel
Dimensions 220 x 507 x 508.6 mm / 8.7 x 20 x 20 inch (W x H x D)
Net Weight 10.4 kg / 22.9 lbs
M/B Type microATX, ATX
5.25″ Drive Bays 3 (exposed)
3.5″ Drive Bays 9 (hidden; 7 in the HDD/SSD combo cage, 1 at the bottom, 1 in the ODD cage by adapter)
2.5″ Drive Bays 10 (hidden; 7 in the HDD/SSD combo cages, 1 under the ODD cage, 1 behind the M/B tray,1 at the bottom)
I/O Panel USB 3.0 x 2, USB 2.0 x 2, Audio x 1 (supports AC97 / HD Audio), Mic x 1, SD card reader (Class 10) x 1
Expansion Slots 7+1
Cooling System Top: 180/200mm fan x 1, or 120/140mm fan x 2 (optional)
Front: 120mm Silencio FP 120 fan x 2 (installed; 11±1 dBA, 1200±200 RPM)
Rear: 120mm Silencio FP 120 fan x 1 (installed; 11±1 dBA, 1200±200 RPM)
Side: 180/200mm fan x 1 (optional)
Bottom: 120/180mm fan x 1 (optional)
HDD cage: 120mm fan x 1 (optional)
Power Supply Type Standard ATX PS2
Maximum Compatibility VGA card length: 423 mm / 16.6 inch
CPU cooler height: 168mm / 6.6 inch

EXTERIOR

The Silencio 652S weighs 10.4 kg or 22.9 lb and like most towers, is constructed
of a combination of steel and plastic. It measures 22.0 x 50.7 x 50.9 cm or
8.7 x 19.9 x 20.0 inches (W x H x D) so the chassis occupies a total volume
56.7 Liters, which is about the going volume for a mid-tower these days. Cooler
Master also offers a shorter microATX version of the came case, the Silencio
352.


The door swings opens about 125° and its interior is lined with
soft foam. It seems fairly sturdy and the magnets securing it are the
perfect strength. Behind it resides power and reset buttons on the right
edge, three ventilated 5.25 inch drive covers at the top, and occupying
the bottom half is a removable dust filter for the two intake fan positions.
The stock fan is a 1200 RPM model with an interesting five-blade design.


The fans are fed by somewhat undersized air slits on the sides of
the front bezel. The front dust filter is essentially unnecessary as
it sits flush against the front door: The side vents bypass the filter
so it doesn’t really block out any dust unless the door is left open.


The top of the case offers the usual assortment of USB 3.0, USB
2.0, and audio ports, but also an SD card slot. It’s a nice bonus that
we’ wixh more manufacturers would include.


A cover on the top of the case slides out to reveal the 2 x 120/140 mm ceiling fan/radiator placements. The filter can be removed as well, as can the entire top panel.


At the back is a single 120 mm exhaust fan with holes for watercooling underneath, and seven ventilated expansion slots (and one extra one on the side).


More removable dust filters can be found on the bottom of the enclosure, one for a combination 120/180 mm fan or 3.5-inch hard drive position, and one for the power supply. Oddly, the PSU vent is moderately smaller than the fan of a typical ATX unit.

SIDE PANELS & INTERIOR

The Silencio 652S is reasonably well constructed for a case near the US$100 price-point. The side panels are on the thin side, but the damping sheets provide some extra heft and stability. All the various panels and filters fit fairly snug as well.


Compared to the lining on the door, the acoustic pads applied to the 0.8 mm thick side panels are thinner and considerably stiffer. The left panel has a removable cover for a giant 180/200 mm fan mount.


The only interesting aspect of the interior is the drive area at the front. The small bottom cage is secured to the floor of the case, while the one above it is actually just two metal sides held together with screws at the front and back. Out of the box, this section supports only 2.5-inch drives, but the inner wall can be repositioned an inch over, expanding it to accommodate 3.5-inch models (the drive trays are designed to extend as well). An additional 3.5-inch drive can be mounted to the floor.


All the steel in front of the intake fans is a serious impediment to airflow. If performance is a priority, I recommend removing one or both of the drive cages.


A third fan is positioned at the rear of the case acting as an exhaust. The case does not include a fan controller, so motherboard fan headers or a third party controller are required to slow down the included fans. Another option is to modify the 4-pin molex adapter (each fan has one included) to give the fans 5V or 7V instead of the usual 12V.


Four small rubber pads elevate the power supply to give it some extra breathing room and reduce vibration. The intake holes on the floor of the case are rather large, making them perfect for swallowing up dropped screws.


The right side of the enclosure is home to one 2.5-inch drive mount,
and a good number of tie-down points and grommeted cable routing holes.
However, space is at a premium as there is only 11~12 mm of clearance
behind the motherboard tray once the useless acoustic damping sheet
on the side panel is accounted for.

ASSEMBLY

There’s nothing complicated about assembling a system inside the Silencio 652S
as it has a traditional tower layout and the usual mounting methods for the
various components. However, some thought is required on how to configure the
hard drives, and the area behind the motherboard tray is cramped, making it
tricky to to get the side panel on when all th cables are tuck away back there.


The plastic drive trays are a two-piece solution that grip together at two different points in order to support both 2.5 and 3.5-inch models. They use a simple side bolt/grommet scheme and can expand wider than necessary so even 3.5-inch drives can be installed/removed without bending the tray.


The sides of the upper drive cage take some serious force to remove but doing so opens up the airflow path of the top intake fan. This also decreases the structural stability of the bottom hard drive cage, so you have to decide which is more important.


The test system fully assembled. I mounted the hard drive in the
bottom cage as it’s more stable, and the upper drive cage restricts
the amount of airflow directed toward the graphics card. The drive snaps
in tight. GPU clearance obviously isn’t an issue. Our Mugen Max has
2.0 cm of space above it, making the CPU cooler height limit a generous
18 cm.


Behind the motherboard tray, the cable tie-down points are well spaced so there are a variety of options for positioning all the wires.


Despite being a somewhat wide tower, the 652S doesn’t offer much
room on this side. Closing the side panel can be a pain if everything
isn’t smartly organized.

TESTING

System Configuration:


Test system device listing.

Measurement and Analysis Tools

  • Prime95
    processor stress software.
  • FurMark
    stability test to stress the integrated GPU.
  • Asus GPU Tweak to monitor GPU temperatures and adjust fan speeds.
  • SpeedFan
    to monitor system temperatures and adjust system fan speeds.
  • Extech 380803 AC power analyzer / data logger for measuring AC system
    power.
  • PC-based spectrum analyzer:
    SpectraPlus with ACO Pacific mic and M-Audio digitalaudio interfaces.
  • Anechoic chamber
    with ambient level of 11 dBA or lower

Testing Procedures

The system is placed in two states: idle, and load using Prime95 (large FFTs setting) and FurMark, an OpenGL
benchmarking and stability testing utility. This puts more demand on the CPU and GPU than any real life application. Throughout testing, system temperatures, noise levels, and power consumption are recorded. During the load test, the system and GPU fans speeds are adjusted to various levels in an attempt to find an optimal balance between cooling and noise while maintaining a GPU temperature of 80°C at 22°C ambient.

Baseline Noise

For our baseline noise tests, the system is left idle, the GPU fans are off completely by default, and the CPU fan is set to its minimum speed while the system fans are set to variety of speeds. This gives our readers a good idea of what the stock fans sound like at different speeds with minimal interference from other sources.

Initially, the system measures 17 dBA@1m in this state which is a bit high,
a result of a strong low-pitched hum caused by hard drive vibration. It’s a
steady buzz rather than the more annoying throbbing resulting from looser drive
configurations, but it’s still unpleasant. The bottom drive cage is held on
securely but only from the bottom; There’s nothing pushing against it from above
or bracing it from behind. The plastic trays also do little to decouple the
drives from the steel frame around it, as the sides press up directly against
one another. Putting the the upper cage back in makes a substantial difference,
reducing the noise to 15 dBA@1m. This however, blocks out quite a bit of airflow
from the upper intake fan.

The top cage was removed and a thick rolled up piece of foam inserted between
the bottom cage and the motherboard tray to try anc reduce the vibration-induced
noise. This created more noise at 120 Hz (corresponding to the 7200 RPM speed
of the drive’s motor) than when both drive cages are in place, but the overall
SPL is 16 dBA@1m, effectively splitting the difference between the stock options.

Baseline Noise Level
(idle, CPU fan at 400 RPM, GPU fans off)
Fan Speed Setting
Fan Speed
SPL @1m
0%
N/A
16 dBA
50%
540 RPM
17 dBA
70%
780 RPM
19~20 dBA
80%
910 RPM
24 dBA
90%
1030 RPM
21~22 dBA
100%
1150 RPM
26 dBA
Measuring mic positioned 1m at diagonal angle left/front
of case.
Ambient noise level: 10~11 dBA@1m.

The Silencio 652S is quieter than most triple fan cases, with the total noise
measuring 26 dBA@1m at full speed. With our system, the fans begin to have an
effect on acoustics at about 500 RPM. Oddly, the machine actually has a lower
measured noise level at 90% than it does at 80% speed. Unfortunately, the quality
of the noise is poor.


Starting at about 700 RPM, the fans have a very dry, growling
sound with multiple competing tones. As the fan speed increases, so does the
pitch, making their negative qualities more prominent. For some reason, at 90%
speed, there is a brief respite, as the most substantial ~300 Hz tone dissipates
at this level, resulting in a drop in SPL of 2~3 dB compared to 80% speed. However,
even with this improvement, they have an unpleasant droning character. The nasty
tone also returns at 100% speed, so the benefit at 90% is an accidental anomaly.
The stock fans simply sound bad at all but the lowest of speeds, a stark contrast
compared to the relatively benign-sounding fans of earlier Silencio models.

Interestingly, this case’s now discontinued predecessor, the Cooler
Master 652 (non-S), sported two fans, a 180 and 120 mm variant, with a more
traditional blade design.

TEST RESULTS.

System Measurements (80°C Target GPU Temp)
System State
Idle
CPU + GPU Load
Avg. System Fan Speed
540 RPM (50%)
540 RPM (50%)
780 RPM (70%)
1030 RPM (90%)
GPU Fan Speed*
Off
1490 RPM (50%)
1360 RPM (47%)
1170 RPM (43%)
CPU Temp
29°C
74°C
70°C
66°C
MB Temp
35°C
51°C
50°C
46°C
SSHD Temp
33°C
35°C
34°C
33°C
GPU Temp
35°C
80°C
80°C
80°C
System Power (AC)
48W
361W
360W
355W
SPL@1m
19 dBA
24~25 dBA
23~24 dBA
23 dBA
*set as low as possible to maintain target GPU temperature on load.
CPU fan at 800 RPM.
Ambient temperature: 22°C.

Sitting idle, the internal temperatures are quite low with the CPU running close to 30°C and the motherboard, SSHD, and GPU at or below 35°C. Keeping the system fans at 50% speed on load causes a sizable increase in thermals for all components aside from the SSHD, which remains mostly unaffected in the cooler portion of the case near the floor. The CPU and motherboard heats up by a massive 45°C and 16°C respectively, and stabilizing the GPU at 80°C requires GPU fan speeds of 1490 RPM (50%). In this state, the machine generates a moderate noise level of 24~25 dBA@1m.

Increasing the system fan speeds to 70% helps cool down the CPU by 4°C and allows the GPU fans to slow by 130 RPM while the noise level drops by 1 dB. 90% proves to generate the best results, lowering both the CPU and motherboard temperature by an extra 4°C, giving the GPU fans an additional respite of 190 RPM, and producing an overall SPL of 23 dBA@1m.

The noise produced by the CPU and GPU fans is a bit of a blessing
in this case as it helps balance out the poor acoustics of the stock fans. Blended
together, the tonality is less conspicuous, and the overall sound more tolerable.
Typically, the GPU fans have the poorest sound, but here they’re actually beneficial.
Hard drive vibration is still an audible aspect of the system’s acoustics. Pressing
down firmly on almost any part of the chassis improves the sound of the machine.

System Measurements: CPU + GPU Load (80°C Target GPU Temp)
Configuration
Stock
Top Cover Off
Avg. System Fan Speed
1030 RPM (90%)
780 RPM (70%)
1030 RPM (90%)
GPU Fan Speed*
1170 RPM (43%)
1360 RPM (47%)
1270 RPM (45%)
1120 RPM (41%)
CPU Temp
66°C
70°C
64°C
62°C
MB Temp
46°C
50°C
48°C
45°C
SSHD Temp
33°C
34°C
32°C
32°C
GPU Temp
80°C
80°C
80°C
80°C
System Power (AC)
355W
360W
354W
352W
SPL@1m
23 dBA
23~24 dBA
23~24 dBA
24 dBA
*set as low as possible to maintain target GPU temperature on load.
CPU fan at 800 RPM.
Ambient temperature: 22°C.

Removing the top fan cover is significantly advantageous at 70% fan speed. The CPU cools down by 6°C while the motherboard and SSHD temperatures drop by 2°C a piece. A small reduction in GPU fan speed offsets the extra noise escaping the case through the ceiling. At 90% fan speed, the thermal difference is noticeable too but less dramatic, and the system SPL actually goes up slightly.

On a side note, the 120 Hz tone from hard drive vibration is lessened somewhat when the top cover is taken off, suggesting that it rattles slightly as the rest of the chassis shakes. The vibration issue may be exacerbated by the 652S’ numerous panels, filters, and covers.

Case Comparison: System Measurements
(CPU + GPU Load, 80°C Target GPU Temp)
Case
SilverStone Fortress FT05
SilverStone Kublai KL05
Cooler Master Silencio 652S
NZXT H440
Avg. System Fan Speed
2 x 500 RPM
2 x 840 RPM (60%)
3 x 1120 RPM (90%)
3 x 810 RPM (60%)
GPU Fan Speed*
1000 RPM
1070 RPM
1120 RPM
1410 RPM
CPU Temp
53°C
57°C
62°C
66°C
MB Temp
36°C
43°C
45°C
51°C
SSHD Temp
33°C
34°C
32°C
36°C
GPU Temp
80°C
80°C
80°C
80°C
System Power (AC)
348W
351W
352W
358W
SPL@1m
21~22 dBA
24 dBA
24 dBA
24 dBA
*set as low as possible to maintain target GPU temperature.
CPU fan at 800 RPM.
Ambient temperature: 22°C.

Our best result with the Silencio 652S isn’t terribly impressive compared to
previously tested cases. At the same 24 dBA@1m noise level, the SilverStone
Kublai KL05, a more affordable budget case, runs cooler across the board.
The 652S does manage to beat the under-ventilated NZXT
H440, but this is not much of an accomplishment.

On load, the hard drive vibration issue doesn’t affect the acoustics in any
measurable way, and the overall airflow scheme seems sound. That leaves the
fans as the probable culprit behind this poor showing. It would seem that not
only do they sound bad, they don’t perform well either, at least as case fans.

AUDIO RECORDINGS

These recordings were made with a high resolution, lab quality, digital recording
system inside SPCR’s own 11 dBA ambient anechoic chamber, then converted to
LAME 128kbps encoded MP3s. We’ve listened long and hard to ensure there is no
audible degradation from the original WAV files to these MP3s. They represent
a quick snapshot of what we heard during the review.

Each recording starts with ambient noise, then 5~10 second segments of product
at various states. For the most realistic results,
set the volume so that the starting ambient level is just barely audible, then
don’t change the volume setting again while comparing all the sound files.

FINAL THOUGHTS

I’ve test dozens of cases for SPCR over the years, but can’t recall one with
such bad sounding fans. And usually letting the system fans do as much heavy
lifting as possible (as the GPU fans typically have worse acoustics) is our
usual approach, but with the Silencio 652S, the opposite is true. The chassis
has damping sheets on the side panels, which really can’t do much to ameliorate
the fan sound quality. (Editor’s Note: We consider most internal
case foam lining to be just a marketing ploy; it hardly does anything for noise
reduction.) It lacks a fan controller, something every noise-conscious multi-fan
case should include unless its fans are lower speed models. Out of the box,
hard drive vibration isn’t an issue but if the upper drive cage is dismantled,
the lower cage’s lack of physical support becomes exposed. The cages are also
fairly restrictive of airflow, impeding the intake fans, even if the individual
drive trays are removed. On a non-noise related front, the amount of space behind
the motherboard tray is limited, making it a challenge to fit the right side
panel.

The 652S’ strengths are more general rather than specific for any one function.
It’s reasonably well-built and manages to pack some degree of versatility while
maintaining an attractive appearance. The door and top cover have an elegant
design that makes the chassis look solid, but this is deceiving. There are many
fan mounts with some support for 180/200 mm models, and the side and top placements
have covers if they’re not being used. The front bezel and the floor of the
chassis are sufficiently ventilated and the removable dust filters are numerous,
easy to access, and not too restrictive, though the front filter serves little
purpose due to a flaw in the bezel design. The chassis is also sufficiently
wide and deep that CPU cooler and video card clearance are non-issues.

The upper hard drive cage and expandable drive trays is a rather clever idea,
allowing users to configure it to support either 2.5-inch or 3.5-inch drives,
or to take it out entirely. However, the design forces users to choose between
increased airflow and lower drive vibration. If you leave this section in, the
case seems like a decent option for a quiet server. With subpar thermal performance
and poor acoustics, this is probably the best usage case for the 652S.

While Cooler Master Silencio 652S is pushed as a premier quiet tower, it falls
well short of this billing. The mediocre stock fans alone are enough to disqualify
it, and while it does have some redeeming qualities, the sum doesn’t have enough
appeal for any particular niche or demographic.

Our thanks to Cooler Master
for the Silencio 652S case sample.

* * *

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* * *

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