Silverstone Air Penetrator SST AP181 Fan review

At KitGuru we believe that good cooling is a primary concern when maintaining stability with a system build, especially if you are overclocking. While we haven't looked at many fans since we opened a few months ago, today we are going to be reviewing an exciting new product from Silverstone called the Air Penetrator.

This Air Penetrator fan has been designed as an intake fan and their goal was to focus airflow into a column that can be ‘channeled through various obstacles inside the modern computer case for more efficient cooling performance'. The concept and design ethics are in place to ensure that the unique blade and grille designs can create enough pressure to push air as far as 1 meter away with minimal speed (and therefore noise). Silverstone are pushing this range of fans as a perfect intake partner and also for high density heatsinks and radiators.

The Silverstone Penetrator fans are rather unique so it is worth having a look at how this fan technology really works when compared to a more traditional fan design.

A normal fan produces air flow in a manner as seen above. Air intake follows the physics of moving from a high pressure area into a low pressure area meaning that air will enter into the fan evenly. Due to centrifugal forces and compression through the fan frame the airflow is spread outwards as it leaves the fan. This actually means there is a dead spot that is slightly wider than the fan hub.

This design is perfectly fine as an exhaust design, however when used as an intake unit it is less than perfect due to this dead spot in the center.

Silverstone went through a long testing time period when looking at fan designs and the image above shows what happens when resistance is added on the intake side – in this case by adding a fan filter. The airflow is spread outwards more than it would be in free air. Additionally, fans with lower air pressure will see a greater ‘outwards effect' than those with higher air pressure.

The image above shows what happens when this is used as an intake fan inside a computer case. Due to the walls of the case the airflow will spread out and travel along the side walls leaving dead space in the middle of the case, this is not an ideal situation, especially if a specific component would benefit from cooling in the center of the area.

This is how Silverstone have been rather ingenious in their new design. Many people who have a Raven 02 will have noticed that they used a honeycomb air guide cover which doubled as a fan guard to improve airflow direction.

These honeycomb holes have an equal depth and are spread in an even manner which helps to create numerous air guide tracts which forces the air upwards in a parallel flow. This also negates dead spots even though the airflow rate will be slightly reduced. Silverstone however took this a stage further.

By adding a fan filter on the intake side and by redesigning the fan grille the ‘Air Penetrator' series dramatically improve airflow efficiency when compared against a more traditional fan design. This uses a combination of fan blades which twist air into a ‘swirl shaped' fan grille and this forces airflow to crest forward in a circular motion which helps to virtually eliminate dead spots. This airflow is very directly focused and can also extend much further. By creating this design ethic and removing a honeycomb grille they have also helped to increase airflow as there is one less ‘material' to travel through on route.

An added benefit of the Air Penetrator grille is that this is built into the frame of the unit and is designed to also act as a fan guard which means you dont need to add another grille for protection. Many of you will remember that in the RV02 and FT02 cases that sometimes the fan grille had to be removed to fit 12.2 inch graphics cards, but this obviously leaves the blades exposed, leading to potential issues.

The Silverstone SG07 is the first chassis to be equipped with an Air Penetrator fan and we have one in our labs already so our review will be published in the very near future. We are excited about this product.

The Silverstone Air Penetrator SST AP181 fan arrives in a cardboard box which is actually offering much more protection than a standard ‘clear package' design we are used to seeing.

The rear of the box focuses on specifications and includes an illustration of the airflow methodology incorporated, we obviously covered this in detail on the last page.

The fan is an impressive looking unit with two cables emitting from the center. One is a simple header connector for a motherboard and there is also a switch included for a low and high speed setting.

The rear of the chassis shows the seven blade design in all its glory.

The blades connect with the hub and you can notice there is a slightly raised ridge just before they enter into the central area – this is to help focus the air.

This header connects to a switch so the user can toggle between 700 and 1,200 rpm for either improved airflow or lower noise.

Two final shots of the fan from both front and rear angled positions. Now its time for the all important testing.

For testing today we are using a Silverstone Raven 02 Chassis

KitGuru AMD reference gaming system:
Processor: AMD Phenom 1055T
Cooler: Noctua NH C12P SE14 Cooler review
Motherboard: MSI 890 GXM-G65
Graphics: PowerColor HD5870 PCS+
PSU: Coolermaster 700w
Hard Drive: Crucial 256GB SSD (review forthcoming)
Memory: Kingston 8GB DDR3 1600mhz

Windows 7 Ultimate Edition 64bit

Thermal Diodes
Raytek Laser Temp Gun 3i LSRC/MT4 Mini Temp
Digital Sound Level Noise Decibel Meter Style 2

The Silverstone Raven 02 Chassis has been a personal favourite of mine for many years and when I reviewed it for another publication I gave it a top rating. My views on this chassis haven't changed, I think its one of the finest cases ever produced and Silverstone created an airflow monster case with a design which is purely based on the laws of physics rather than a traditional front to rear flowing system.

Heat rises, it is a basic principle, and before Silverstone released the Raven 02, I always wondered why a chassis manufacturer had yet to release a vertically designed air flow system. Fans at the bottom, forcing air upwards, across all the components and expelled outwards. Why battle against a natural system when you can use it to work for you? The Raven 03 will be with us shortly, so we hope it makes as positive an impact with us as the 2nd revision did.

For the purposes of monitoring air flow and how this fan improves cooling, we are going to swap out the second (middle) fan in the Raven 02 chassis with the new Penetrator AP181. This means that direct airflow over the position of the PowerColor HD5870 PCS+ graphics card. We selected this card for a very specific reason.

We attached two diodes to the heatpipes on the Powercolor PCS+ graphics card as shown above and will monitor the temperatures with the standard fan in the Raven 02 and the new Penetrator design, this is a great real world test to see if it brings any additional cooling to the table. The heatpipes get very hot on this card under load so its an ideal way to test performance – we measure load after 45 minutes of running Furmark. Card Ambient temperatures are measured a few mm from the surface of the rear of the PCB.

Laboratory room climate is maintained at a steady 25c with air conditioning. All fans are set to high.

It is clear to see that our testing shows much more focused air flow with the new Penetrator design resulting in a reduction of several degrees with both our positional diodes and even ambient air temperature in the vicinity of the hot running PCB has been reduced.

As the noise levels are a little higher than we like (more on this later), we retested with all fans at low speed settings.

While the noise levels are reduced dramatically it is clear that the temperatures are hardly affected at all by the slightly lower spinning speeds … clearly due to the low ambient case temperatures with the three fans working in tandem. An excellent set of results for Silverstone, even for their older fan design.

Recently we have changed our method of measuring noise levels. We have built a system inside a Lian Li chassis with no case fans and have used a fanless cooler on our CPU. We are using a heatpipe based passive power supply and an Intel SSD to keep noise levels to a minimum. The motherboard is  passively cooled and we use a Sapphire HD5670 Ultimate Edition graphics card which is also passively cooled. Ambient noise in the room is kept as low as possible. We measure from a distance of around 1 meter from the chassis and 4 foot from the ground to mirror a real world situation.

Why do this? Well this means we can eliminate secondary noise pollution in the test room and concentrate on only the components we are testing. It also brings us slightly closer to industry standards, such as DIN 45635.

In this instance we have no need for a system so we are using a silent power supply hooked into the Penetrator AP181 fan. The room rates as 21dBa  – the air conditioning unit in the far corner of the room causes this.

KitGuru noise guide
10dBA – Normal Breathing/Rustling Leaves
20-25dBA – Whisper
30dBA – High Quality Computer fan
40dBA – A Bubbling Brook, or a Refridgerator
50dBA – Normal Conversation
60dBA – Laughter
70dBA – Vacuum Cleaner or Hairdryer
80dBA – City Traffic or a Garbage Disposal
90dBA – Motorcycle or Lawnmower
100dBA – MP3 player at maximum output
110dBA – Orchestra
120dBA – Front row rock concert/Jet Engine
130dBA – Threshold of Pain
140dBA – Military Jet takeoff/Gunshot (close range)
160dBA – Instant Perforation of eardrum

On low settings the fan is basically silent and only shows up on our recording equipment, slightly above ambient room noise. When switched to high speeds however the fan becomes clearly audible, even to the naked ear. We would opt for the low setting all the time, unless we were trying to break overclocking records with a system build.

Silverstone really do deserve a lot of credit for the creation of the Penetrator fan, it is not just an effective design, but this company are clearly trying to push the boundaries of both chassis and fan design by spending a lot of R&D cash to emerge with creative new solutions.

While we have done all the real world testing today and explained how the technology has advanced fan design, the video above is a great visual indicator of exactly how the air flow has changed when compared to a traditionally design fan ethic.

The fan is not only well constructed and designed but you have the option of two speed settings. At low settings we were rewarded with low temperatures on the heatpipes during real world testing with the added benefit of virtually no noise at all. At high setting the noise became noticeable, but within a general enthusiast gaming chassis, 34dBa would be quieter than most CPU or chassis fans. This is a choice Silverstone have handed to the customer, and is something we like to see.

In the UK, the consumer cost is just under £15 inc vat which is clearly a very competitive price, especially for such a large fan with a radical new design implementation.

KitGuru says: If you are looking for a new chassis fan and your case can handle the size, then this should be on your shortlist.

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