Aerocool AeroEngine II

Krazy Kommando · Post by **Krazy Kommando** » Tue Oct 18, 2005 10:15 pm

http://hi-techreviews.com/reviews/AeroE ... 0II/P1.htm

what do you guys think of this case? the front 14cm fan looks like a larger version of their 12cm Turbine fans (which are VERY quiet like nexus's). Its rear 12cm fan grill isnt so great, but thats an easy fix. Although it does have a rather open front. The CD bays are mesh, and there is nothing covering the front fan (good performance, possibly bad for a quiet point of view). With isolated HDD's, it should be reasonably good. What do you think?

Freelancer77 · Post by **Freelancer77** » Thu Oct 20, 2005 12:11 am

Hmmm. Let's see.

1. Bolt-on window, with no apparent seal around the mating surface between the 'glas and the side panel.

2. Exhaust grille is utter garbage, especially in light of how much attention the intake gets.

3. No-go showboat split front door segments, made of the same low-grade insta-break plastic as the main bezel.

4. Screw-on drive mounts. No sign of drive isolation anywhere.

5. Half-baked job of turning metal edges. There are sharp edges everywhere, in spite of the "look" of safely turned steel.

6. Bigger intake fan than exhaust suggests a positive pressure inside the case. Fine, some folks believe that's better for cooling than negative pressure. So why all the extra ventilation, as on the right side panel?

7. The motherboard tray is not firmly mounted in the case, yet it isn't removable.

8. The metal work is all second rate. The stamping, the riveting, the uneven edges (take a close look at the holes in the motherboard tray for an example).

When this case showed up in a local shop I had to take a look, given the bold facade. Sadly, that's it's best and only notable feature.

I can't comment on performance in the quiet or cool realm, as I have not seen or read of one built up and tested. The review linked above fails badly in that regard.

"If you were to load the AeroEngine II fan slots up with 120mm fans you would have a total of four of them operating in your system. I'm quite positive that the system would operate about as close to room temperature as was physically possible. It also might require you to wear some sort of ear protection since 4 fans might just about be to many."

Those are review comments? He bothered to fit a system, but didn't run it. No as-tested comments regarding temperature or noise. But he really likes the looks of the bezel. I have four 120mm fans running in my P180, and it's the quietest rig I've ever owned, no "ear protection" required. I don't think I'll be referring anyone to a site that is named for reviews, but can't do a proper review. Of course all of that is beside the point of the case itself.

stromgald · Post by **stromgald** » Thu Oct 20, 2005 7:53 am

What a half baked review. Seems like the only thing the guy cared about was the cool looks of the case and the 14 cm fan up front. I agree with most of the points that Freelancer makes. And to tack on another, it claims to be very light weight and 0.65mm SECC as its material. That is very thin, most computer cases go for 0.8mm or 1mm. Even though it is steel there may be quite a bit of resonance especially with hard mounted hard disks.

The case manufacturer was definitely more focused on looks and style rather than performance. The 14mm fan up front is probably a gimmick for people who like big numbers. The main reason most manufcaturers don't use 14cm fans is that they create a lot of turbulence noise, to avoid that, the fan needs to turn even slower than quiet 12 cm fans do now. Even if it is quiet, the way its positioned with the mesh grill leads to alot of noise leakage out front where most people sit relative to their computers.

Krazy Kommando · Post by **Krazy Kommando** » Thu Oct 20, 2005 8:37 pm

yeah i guess you guys are right. my search for a stylish & quiet case continues!

Freelancer77 · Post by **Freelancer77** » Sun Oct 23, 2005 10:12 pm

Just a small point I think worth making, thinking back on the P150 review by Ralf.

It seems that everyone is taking to a "bigger is better" view of fans, which might be responsible for Aerocool putting a 140mm job in the intake of that case, thinking to capitalize on the trend by outdoing the 120mm intake fans found on many currently popular cases. While it is true that a larger fan can move more air at a slower RPM, that isn't the only piece of the whole puzzle. From Ralf's article:

I've experimented lots with 120mm intake fans and have come to the conclusion that they are almost always overkill. The front intake fan rarely aids much in actual cooling, and is mostly useful for cooling the HDD(s). In the role of HDD cooling, any 120mm fan is serious overkill. Even a 120mm Nexus Real Silent running at 5V supplies much more air than needed. Over the years, I've generally opted to use a super quiet 5-volt 80mm or 92mm fan mounted right onto the 120mm fan grill for HDD cooling. This provides more than enough airflow, and is usually quieter than a 120mm solution, something that's very important considering the front fan is the closest source of noise escaping from the case.

Unlike the "reviewer" of the Aerocool case, Ralf takes the details very seriously, and always backs up his comments with tested results. Certainly in a mid-size case, a 92mm intake and a 120 exhaust are enough for almost any configuration. In a case such as the P180, with 11-drive capacity and a much larger interior, provision for more airflow is desirable, though most P180 users don't need to employ an intake fan at all.

All that said, my first complaint about the Aerocool case's fan arrangement still holds. A monster fan in front, and a very poor grille for the exhaust 120mm makes for a significant positive pressure condition inside, which simple physics will show is less desirable for cooling. With a direct relationship between pressure and temperature in a fixed volume vessel, lowering pressure will always lower temperature. The positive pressure condition also tends to support greater turbulence noise from the fans, and near the intake where it is least desirable. It is almost always better, for both cooling and quiet, to have less intake fan volume than exhaust.

Krazy Kommando · Post by **Krazy Kommando** » Sun Oct 23, 2005 10:16 pm

theres one thing that i dont understand about that. why would a 80/92mm fan at 5v be quieter than a 120mm fan at 5v?

ckolivas · Post by **ckolivas** » Mon Oct 24, 2005 12:37 am

Krazy Kommando wrote:theres one thing that i dont understand about that. why would a 80/92mm fan at 5v be quieter than a 120mm fan at 12v?

If all else is equal with the fans, the 120mm fan at 12v produces more noise than a 92mm fan at 12v which produces more noise than an 80mm fan at 12v. Bigger is not better, it just happens to produce less noise - at the same airflow - as a smaller fan. If you have more airflow than you need you end up having more noise than you need.

Krazy Kommando · Post by **Krazy Kommando** » Mon Oct 24, 2005 2:32 am

so the best overall fan configuration for the average case, would be a 120mm exhaust fan and an 80mm intake? im just surprised to hear this because most of the time ppl are always saying bigger is better when i comes to case fans...

ckolivas · Post by **ckolivas** » Mon Oct 24, 2005 2:36 am

Krazy Kommando wrote:so the best overall fan configuration for the average case, would be a 120mm exhaust fan and an 80mm intake? im just surprised to hear this because most of the time ppl are always saying bigger is better when i comes to case fans...

Depends entirely on your airflow requirements, most pcs are happy with very little airflow as long as there is some and the case is designed well for airflow. If you have a pentiumD dual core and a 7800gtx graphics card then you'll need a back yard blower to keep it cool, but a well thought out pc with low heat producing components can be satisfied with a single 80mm fan.

Bluefront · Post by **Bluefront** » Mon Oct 24, 2005 3:32 am

Humm....You suggest a 120mm exhaust fan and a slow-running 80mm intake fan?

What that will do is insure air will be sucked into the case from any available opening....through the optical drive for instance. Or maybe through the small openings around the ports....anywhere possible. This air will then go straight to the exhaust fan and probably miss the hard drives completely.....and it will probably miss other hot spots as well.

Not to mention.....this negative pressure will draw in dust as it enters, because all the little openings cannot be filtered.

The solution...a quiet intake system that does not draw air from the front of the case, filters in front of the intake fan, a neutral pressure case with about the same amount of air blown in as is blown out, ducting to control where the airflow goes in relation to the hot components.

Insuring that the air flowing through the case actualy cools the hot components is the key to quiet running.....IMHO of course.

Krazy Kommando · Post by **Krazy Kommando** » Mon Oct 24, 2005 3:38 am

so its best to have a neutral presure (which is what i thought). thus, its best to have either an 80mm exhaust and intake, or a 120mm exhaust and intake. and since i dont think x2 80mm's would properly cool the components at a quiet level, then x2 120mm's would be optimal? or would it be best to have a 120mm exhaust, and x2 80mm intake fans?
i guess what im trying to find, is what is the optimal cooling setup for a mid-range rig? (such as mine, in sig)

Bluefront · Post by **Bluefront** » Mon Oct 24, 2005 4:45 pm

This whole airflow subject with relation to computer cooling/quieting is filled with variables, and subject to much debate.

I have put together a large number of systems, trying to find the optimal setup...still working on it. But what I suggested works well and is very quiet because it'll run with low airflow with a number of different CPU heatsinks.

I go to great lengths to prevent air entering the case except exactly where I want it. It insures the hard drives benefit from all incoming air. But there are so many ways to accomplish this, I cannot recommend any one "best" way.....

Krazy Kommando · Post by **Krazy Kommando** » Mon Oct 24, 2005 5:12 pm

aha! how i know why ive caused so much confussion, silly me. instead of writing:

theres one thing that i dont understand about that. why would a 80/92mm fan at 5v be quieter than a 120mm fan at 5v?

i wrote

theres one thing that i dont understand about that. why would a 80/92mm fan at 5v be quieter than a 120mm fan at 12v?

its a pitty that there is no real "best way" to setup case fans

i guess ill have to keep on the look out for a nice case with x2 120mm's or x1 120mm and x2 80mm's. i dont think there would be many other combinations around that would give a neutral/slight negative presure.

ckolivas · Post by **ckolivas** » Mon Oct 24, 2005 5:14 pm

Krazy Kommando wrote:aha! how i know why ive caused so much confussion, silly me. instead of writing:
theres one thing that i dont understand about that. why would a 80/92mm fan at 5v be quieter than a 120mm fan at 5v?
i wrote
theres one thing that i dont understand about that. why would a 80/92mm fan at 5v be quieter than a 120mm fan at 12v?

An 80mm fan at 5v is still significantly quieter than a 120mm fan at 5v (assuming they're the same low speed range type fans and quality production etc).

stromgald · Post by **stromgald** » Mon Oct 24, 2005 7:29 pm

Turbulence. As fans get bigger, they produce more turbulence. Vorticies created by the tips of the fans become stronger/larger and create more noise. This is because the radius gets bigger; so for the same rpm, the tip of the fans are actually moving faster (tangentially). However, like ckvolias said, they usually move more airflow at the same noise levels. Generally, cfm/dba is better as fans get larger; however, dba/rpm is worse. The exact relationship probably also varies by number of fan blades and blade shape.

For example: a 120mm fan generates 25dba at 1500rpm, and moves 40cfm; a 140mm fan or similar design also generating 25dba would have to be moving at less than 1500rpm and probably moves more air. The real limits IMO is how slow you can get the fan motor to go, and the effect of the larger vorticies/turbulence.

Krazy Kommando · Post by **Krazy Kommando** » Mon Oct 24, 2005 8:00 pm

alright, thanks for clearing that up for me

although it basically means that all fans are bad (which is what i would have expected from an SPCR member

), at least i understand which ones are better than others in certain applications

ckolivas · Post by **ckolivas** » Mon Oct 24, 2005 9:27 pm

Indeed. The answer to the ultimate question of what fan size to use is simple in theory but tricky in practice. You need to know the maximum airflow you require for adequate cooling, and then find the size that produces that airflow at the lowest speed it reliably runs at. So look at the CFMs produced by the different sizes at 7V (since most fans start reliably at 7V) and then find the smallest size which produces the airflow you require. The hard part is actually knowing the airflow you require though

Freelancer77 · Post by **Freelancer77** » Sun Oct 30, 2005 4:31 pm

Physics.

The velocity at the blade tip of a 120mm diameter fan turning at 1500RPM is just shy of 17Kph. For an 80mm fan at the same RPM the tip velocity is just around 11.3Kph.

All other things being equal (blade count, density, shape, etc.) More noise will ALWAYS be created by an object moving through air at a higher velocity.

The reason larger fans are more desirable is also shown through simple physics.

The area of influence of a 120mm diameter fan is at least 2.5 times as great as that of an 80mm fan, even accounting for the dead zone for the motor in the center.

Again, all other things being equal, the larger fan will move the same amount of air while turning at a MUCH lower RPM; less blade velocity, therefore less turbulence, therefore less noise.

If the airflow requirements for a particular case are completely met by a single 60mm fan turning at low speed, that would be the most desirable of all scenarios. Obviously that wouldn't come close to being enough airflow for most modern systems. Once case structure, component configuration and all of the other variables enter the picture, it isn't so simple.

Bluefront is right, that a negative-pressure case interior will draw dust. That does not negate the fact that air temperature will always be lower in a negative-pressure enclosure than a neutral- or positive-pressure one.

The P-180 has a built-in solution to the dust issue. With all of the "dust intrusion" areas being in the front, the bezel/front door itself provides the method. I have lined the bezel vents (including the large bottom hole) of my P-180 with a very thin, very lightweight open-celled foam. With the total volume of air being drawn in through the bezel, airflow is not reduced enough to compromise cooling. It is reduced, and if I leave the door open I see a 1~2C difference after about 15 minutes compared to closed, but none of the temps inside this case are troubling even at max loading, and my rig is in a dust-prone room.