The airflow inside my case

[TomMe]

Like a few other people on this forum, I had issues with my Seasonic S12-430 in that it would blow out hot air through its rear vents that would heat up my CD and DVD-writers. Also, when I touched the upper back of the case it was relatively warm.
After reading a bit I decided to tape shut the side panel hole and both rear holes and install a front intake fan. That didn't help one bit.

I removed the intake fan and placed it at the bottom rear exhaust hole. That worked beatifully! Now the space between my writers acts as an intake, keeping my drives cool.

Now I have a couple of questions. Can anyone tell me why exactly the first method failed and the second one worked? I have my suspicions, but I'd like to know the opinion of people who know what they're talking about.

Then, I noticed I have 2 front intakes. One at the bottom, and one in front of my 2nd hard drive bay. These are currently pulling in air as well, should I tape one or both of them shut or leave it as it is?

And finally, how can I improve the airflow inside my case? I'm going to put in an AM2 system soon. Will the CPU cooler influence my current airflow? I was thinking about getting an Arctic Cooling Alpine 64, which has a fan that pushes air. Mine currently pulls air.
And also, what about these air ducts? Would I be able to improve things inside my case with one?

edit: Right, here's a look into my case

Tia!

[IsaacKuo]

Can anyone tell me why exactly the first method failed and the second one worked?

Your first method sounds like almost exactly the wrong thing to do to try and keep your optical drives cool. There are three basic "strategies" for airflow:

1. Negative pressure - The typical strategy, with the PSU fan and rear case fan pulling air outside the case. All other openings become de facto intakes.

2. Positive pressure - A custom strategy using intake fans only, or much more intake fan airflow than exhaust fan airflow. All other openings become de facto exhausts.

and

3. Neutral pressure - A strategy of using both intake fans and exhaust fans in roughly equal amounts. Airflow bypasses any other openings.

Your first attempt seems to be neutral pressure, with an intake fan roughly matched by the PSU exhaust fan. Thus, the air pressure within the case would be similar to the air pressure outside the case. This provides no incentive for air to flow either into or out of the case past the optical drives.

Then, I noticed I have 2 front intakes. One at the bottom, and one in front of my 2nd hard drive bay. These are currently pulling in air as well, should I tape one or both of them shut or leave it as it is?

Since you now have only exhaust fans, your case has negative internal pressure. All openings will pull air into the case, including those two front intakes.

The amount of airflow through each intake will be roughly proportional to the intake area. You can improve airflow to some areas at the expense of other areas by blocking off intakes as desired. I would suggest that you at least keep the intake next to the hard drives open--hard drive cooling is very important!

And finally, how can I improve the airflow inside my case? I'm going to put in an AM2 system soon.

I'm not sure about your case in particular, but I notice that most cases have severely restricted intakes. The quick and dirty solution to this is to open up the PCI slot backplanes--but this can reduce airflow to the hard drives.

Will the CPU cooler influence my current airflow? I was thinking about getting an Arctic Cooling Alpine 64, which has a fan that pushes air. Mine currently pulls air.
And also, what about these air ducts? Would I be able to improve things inside my case with one?

Ducting is more of a technique to reduce noise by eliminating fans, rather than a technique to improve airflow. For example, a typical tower heatsink has a fan blowing rearward toward the rear exhaust. This exhaust typically has an exhaust fan. With both fans running, there's no need for a duct. The airflow is more or less ideal that way. However, with a duct it's possible to remove one of the fans without reducing the airflow much.

[NeilBlanchard]

Hello Tom,

I've seen these threads that you are referring to, and I think that it is virtually impossible for the tiny amount of air that comes out of these vents to cause any appreciable warming of the optical drives! This is a theory, and it needs to be debunked.

First of all: how do you know that your optical drives are "overheating"? If they produce a lot of heat within the drives, then try putting a fan blowing onto them? Somehow, I doubt that heat is affecting the use of the optical drives at all...unless the entire system is running very hot.

If the PS is actually running that hot, is the fan running at a high speed? What proportion of the air that it moves actually comes out of the rear vents? I can assure you that a large majority comes out of the honeycomb grill, and goes outside the case.

Do you have another exhaust fan in the case? What about an intake fan? What are the system and ambient temps?

I tend to run my systems with a slight negative pressure, and I worry a lot more about the HD temps. The optical drives in my systems tend to need cleaning due to dust leaking in through the drawer, etc., and so cleaning them (along with the rest of the system) is all I ever worry about.

[TomMe]

Thanks IsaacKuo for your clear answer! I thought it had something to do with negative pressure. The reason I tried the first method is because I read different opinions on different methods, this confused me a bit. But anyway, now I know which works best for me.
What about CPU fans that either push or pull, will these different methods interact differently with the case airflow?

NeilBlanchard, I know some people here are sceptic about this "heating issue". I'm sorry to say that these people are wrong. Debunking would only lead to ignoring a fact. I know it's a fact because I (and other forum members) experienced this first hand.

How did I know my drives were overheating? I never said they were overheating, just hotter than usual. I first noticed this a while after I installed my new PSU. I felt that the upper back of the case was warm, that was a first one.. Then I put my hand in between my drives..they were warmer than before as well. I then felt warm air blowing in my face when I looked straight between the drives and I confirmed this by using a piece of paper to see if it gets pushed or pulled when hanging in front of the drives. Now it gets pulled in.

Before I taped them over, the rear holes were pulling in air and the side panel hole was pushing out. The PSU was pushing out air as well, roughly at the same rate as it does right now. That never changed really.

I haven't found proof, one way or the other..so I can't say for sure that this heat will interfere with the burn quality of writable discs, but it's not something I'm willing to risk. And having heat thrown into your case is never good I guess.

As for my case setup, I think I described it in my first post. Pics included.

edits: cleaning up after the mess..

[JazzJackRabbit]

Hello Tom,

I've seen these threads that you are referring to, and I think that it is virtually impossible for the tiny amount of air that comes out of these vents to cause any appreciable warming of the optical drives! This is a theory, and it needs to be debunked. [. . . ]

There is nothing to debunk here because it's all true. I had the same problem with Enermax noisetaker dual fan design exhausting hot air inside the case. The symptoms are exactly the same as TomMe described. The PSU itself was cool to the touch even with the fans spinning at absolute lowest RPMs, but the top of my case was warm to the touch wherever the rest of the temps were fine and yes my optical drives were also very warm to the touch even when not in use. When I would open the case I could literally feel the pocket of hot air at the top of the case. That's all because that "tiny amount of air" had nowhere to escape so it circulated around the top of the case. Putting an exhaust fan at the top of the case solved the problem. If you remember Nina solved the problem similarly by ducting the hot air through one of the pront 5.25" slots. So no, it's not a myth, it's real.

[NeilBlanchard]

Greetings,

C'mon folks -- all the hottest air rises to the top of the case -- of course the top of the case gets warm. The simplest "fix" is to mount the optical drives in the lower bays.

Why do you think SeaSonic and the other 120mm fanned PS's put those slots there? Just to warm up the top of the case? Or, possibly to allow a little air flow, in what otherwise would be a still-zone in the top back corner of the inside of the PS?

I have built almost all my systems with 120mm fanned PS's (Fortron & SeaSonic), and I have never noticed any problems with the optical drives getting too warm. You can keep tilting at windmills, if you want, and conquer them all -- but I'd rather solve more pressing problems.

[TomMe]

Greetings,

C'mon folks -- all the hottest air rises to the top of the case -- of course the top of the case gets warm.

Not anymore with me.

The simplest "fix" is to mount the optical drives in the lower bays.

The Seasonic's rear vents are at the height of the 2nd lowest bay

Why do you think SeaSonic and the other 120mm fanned PS's put those slots there? Just to warm up the top of the case? Or, possibly to allow a little air flow, in what otherwise would be a still-zone in the top back corner of the inside of the PS?

My previous PSU had similar vents, but since it had an 80mm outtake, the air went out the back of the case.
These vents now probably act as intakes, keeping those parts cool.

I have built almost all my systems with 120mm fanned PS's (Fortron & SeaSonic), and I have never noticed any problems with the optical drives getting too warm.

The better for you, but some of us actually have. I'm sorry to see that you don't take us seriously. But it's not because you haven't experienced the problem yourself, that it's nonexistant.

Greets.