Airflow advice for a guy w/Seasonic Tornado PSU (now w/pics)

[aston]

I'm the proud new owner of a 120mm top blowhole which I cut myself using Crisspy's excellent tin snips tutorial. But what I had in mind -- having it blow up to exhaust hot air out of the case -- isn't working very well.

I have a case with a Seasonic Super Tornado (120mm fan blowing hot air up into the PSU innards), two rear 80mm fans, and the 120mm fan at the top of the case. My system generates a fair amount of heat:

- Barton XP2500+ @ 2.2GHz w/Zalman 7000AlCu
- Radeon 9700Pro w/Zalman HP80A
- two Barracuda IV hard drives

As most Seasonic Tornado PSU owners know, it's been a real $#*@! getting the fan speed to not ramp up. I managed to help the cause by making the 120mm top blowhole + the two rear 80mm fans blow in instead of out, thus providing cooler air for the PSU.

(I thought that reversing either the 120mm top fan or the two 80mm rear fans would create a nice channel for airflow, but doing either of these things just makes the PSU fan ramp up.)

Now, this setup obviously isn't great for airflow -- basically I'm just pushing as much cool air as I can into my case. Now I'm thinking of replacing the 120mm fan in the PSU with one I can control with my fanbus. Should I keep my current fan configuration, or reverse one of the top/rear fans, or reverse them both, or...?

Also, am I going to build up an excessive amount of dust in my box this way?

[1398342003]

Where is fresh air being drawn into the case? It may be that the vents are too small or are obstructed. An option would be to use the 80mm fans as intake fans, and have the 120mm as an exaust fan.

Some pics, or a good description would be useful.

From what I have heard, having a negative pressure case is worse for dust buildup than positive pressure. It has been reported to build up in the CD/DVD drives, though it could occurr almost anywhere.

[acaurora]

Replace 120mm fan in yoru PSU with one that you can control with your fanbus? How does that work?

Personally I think your setup looks jsut fine... blowhole blowing out, PSU blowing out, dual 80mms blowing in.

The only thing I'm concerfned about is where these dual 80mms are (in the back, like, at the bottom? middle? etc), because it may just be recycling hot air coming out of your PSU if it's close enough. Hot air rises, but if your fans are powerful enough, it can sink back and get sucked back in.

[aston]

Here's a picture of my setup. (Forgive the crappy red arrows -- they show which way the air is going.)



As you can see, fresh air is drawn in from the two 80mm rear fans and the top blowhole (or suckhole, in this case). The top blowhole is not blowing out, but in. Air is being exhausted exclusively by the PSU. There are no other fans in the case.

Again, I don't think this is the best setup, but it is the one that's lowered my PSU fan speed the most.

[greenhorn]

If your case has feet, best thing you could do would be to snip out as much of the bottom of your case as possible and then cover it with 1/4" open cell foam(sold as intake filter material for room AC units). Ideally you'd want to adhere it with caulk, but double sided tape would work.

It may sound extreme, but this would provide ample airflow while keeping dust out and also allow you to spin your fans slower by reducing static pressure in your case. Fans would blow out of course.

[NeilBlanchard]

Hello:

As others have mentioned, you really need better intake flow -- you are forcing all the exhaust air (with all the heat gained from the hot bits) *out* through the PS!? If you cut out the front grill, and put on a nominal filter to keep out the *big* dust bunnies, then I would run the PS and the top blow hole *only*. You'll then get cooler air pulled over the HD's and the CPU gets air from the rear as well.

Pushing air is pretty tough to do -- but pulling it is much easier. Air "abhors" a vacuum and it will rush to fill it, and this means that pushing air into a case causes the air to leak back through the fan itself! You cannot use fans as pumps to presurize the case -- against the static pressure they loose their efficiency rather quickly.

But, you need to open up the intakes of the case to get this to work!

[acaurora]

Yah, u need to get that 120mm @ the top to blow out... because if you're having all that hot air going through your PSU... not a good idea. And those Panaflos of yours may just be recycling the hot air, sucking it in from above, then the PSU sucks it in again, and you have this continuous loop of forever-heating hot air.

So what I think you should do is basically just flip the 120 at the top, the 80mms, and then do what Neil mentioned, to use that open cell foam at the bottom. Sounds like a good plan

[1398342003]

Open the lower front of the case, use what ever tools you have access to. Several rectangular slots would do fine. If you have done this already, you could try to cut holes in the side panel. The grey areas in the following image are where you should add extra holes. Focus primarily on the front area near the HDDs, or in the area near the cardslots.



If you don't want to cut metal away, you could try running the fans at the front of the case.

If you want to keep the fans in their current positions you could take out the covers for the CD bays. All of them.

[acaurora]

If you want to keep the fans in their current positions you could take out the covers for the CD bays. All of them.

... you ARE aware that by doing that, you are exposing your computer to TONS of air... and TONS AND TONS AND TONS of DUST!!!!!!!

If you must resort to removing all the bay covers, put some type of dust filter or something. -_-;;. Also, removing those covers exposes your computer's innards, which thus increases your computer's noise, right back at ya =[

[1398342003]

Everyone else was recommending the use of filters, I didn't feel the need to repeat it. Besides, if your computer has terrible heat problems, you may have to risk dust and slightly increased noise levels to fix them.

I recommend what I would do given the situation, always.

BTW aston, what are your CPU temps in the two different setups? (blowing in or out)

[acaurora]

Dust can cause more heat, and can seriously screw up your hardware. That's what I'm saying.

[ONEshot]

He's saying that he believes in filtering.

[acaurora]

Oh. . .

NEVERMIND!!! ^.^

[aston]

So many replies... where to start...

If your case has feet, best thing you could do would be to snip out as much of the bottom of your case as possible and then cover it with 1/4" open cell foam(sold as intake filter material for room AC units).

Unfortunately, this case doesn't have feet, so there's no room for airflow from the bottom of the case. If I get really desperate, maybe I'll add wheels to the case, but I don't think I'm ready for such a time-consuming task yet (plus, I think feet/wheels would make the case ugly ).

Air "abhors" a vacuum and it will rush to fill it, and this means that pushing air into a case causes the air to leak back through the fan itself! You cannot use fans as pumps to presurize the case -- against the static pressure they loose their efficiency rather quickly.

Is this why sometimes I feel air coming out the opposite way that a fan is mounted? E.g. I can put my hand close to the fan in my PSU, which is blowing towards the PSU, but I can still feel some air being pushed against my hand.

BTW, what's "static" pressure? I'm familiar with the terms positive and negative pressure... does static pressure have anything to do with that?

Open the lower front of the case, use what ever tools you have access to. Several rectangular slots would do fine. If you have done this already, you could try to cut holes in the side panel. The grey areas in the following image are where you should add extra holes. Focus primarily on the front area near the HDDs, or in the area near the cardslots.

I'll consider that, thanks. I'd rather not have to cut more holes than I really have to, but again, if I'm desperate for airflow, I might just do that. It would certainly be easier than adding feet and cutting out the bottom of the case.

Unfortunately, I can't cut holes in the font of my case. The front is acrylic. It's got holes in the front for airflow, but I can't imagine much gets in. Another problem with this is that my HDs get scaldingly hot -- with my new fan configuration (see below!), my Seagate Barracuda IVs were up to 56C (using the internal sensor). I love the look of acrylic, but it ain't good for airflow.

If you must resort to removing all the bay covers, put some type of dust filter or something.

I've tested this before, and it does wonders for the case temp. Unfortunately, it also looks ugly, and like you said, it's not good for dust. What I'd like is something that looks like modder's mesh that could replace two of my 5 1/4" drive bay covers, but preferably with a filter. Can anyone recommend anything like this?

And now, for my new fan configuration:

It hit me like a ton of bricks -- I don't know why I didn't think about this before. To silence the PSU, I can just flip it upside down and cut another hole at the top of the case so that it gets fresh air! This way, I manage to isolate the PSU airflow from the rest of the system -- it's kind of like the fresh air channel idea for PSUs with rear exhaust fans. The airflow would go something like this (red arrows indicate fans, green arrow indicates no fan but shows where the PSU would exhaust):



I guess I'm lucky that the PSU fits this way inside my case, though I haven't tried mounting the backplate that secures the PSU to the case... but that shouldn't be much of a problem.

The only thing I'm worried about is crap falling into the PSU. I'm already kind of worried about stuff falling into my existing 120mm blowhole... I'm loathe to think what might happen if a screw fell into the PSU while the computer was running. Maybe a filter will do the trick -- I really should filter dust anyways. Again, can anyone recommend a pretty filter?

I haven't actually cut the top hole yet, but I'll let you all know how it goes.

[peerke]

This is spooky: You seem to have (mostly) the exact same hardware that I'm using.

This is mine:
Case, Jou Jye acrilic (black)
MB, Abit nf7-s
CPU cooler, Zalman 7000cu
NB cooler, Zalman 47nb
VGA cooler, Zalman zm80c
2 optical drives, Plextor cd-burner + LG dvd-burner
1 harddisk, old Maxtor
PSU, Seasonic ss300 (i.e. with 1 80mm L1a-fan)
3 panaflo L1a fans, 2 L1a's for exhaust and 1 over the VGA cooler

Here's what I did:
For intake-air I cut out two large square holes in the bottom of the case using a nibbler (very easy to do) and put it on small feet . My harddisk is resting on a piece of camping-foam over one of them in a smart-drive enclosure, so that it sits in the intake airflow.
For exhaust I'm using 1 L1a fan on the backplate in the lower position where it's bussy exhausting the VGA-heat.
Now this is where it gets complicated: I wanted to stop the psu from ramping up so I wanted to duct it to the top front-bay. But I also wanted to have an exhaust-fan as high in the case as possible and preferably exhausting up (like in your setup). Therefore I moved the PSU as far forward and upward in the case as possible and made some brackets to keep it there. This left me with a cavity where the PSU used to sit. This cavity I sealed off from the case with a panel, leaving the original PSU case-gap open for air to escape to the outside. In this panel I put my second L1a exhausting case-air up in the cavity. The PSU is exhausting it's air into the same cavity.
This setup is working well for me and maybe you can do something similar. I would really suggest you open up the bottom of your case and put it on small feet. As for flipping your PSU; this is a good idea but I think that a second top-hole would not benefit the looks of the case. If you can manage to move your PSU under the hole you already made, you wouldn't have to cut a second one.

[acaurora]

While the flipped PSU idea is good, i still think that your overall airflow plan still needs to be revised. Use the top 120mm to blow air out, and the other 2 80mms to blow air in. That way, fresh, COLD air reaches the CPU, graphics card, etc, and then as it carries away the heat, which, NATURALLY RISES, can be sucked out before it heats up other components.

With the setup as you imagine it, the air coming in from the top will be warmer than if you pulled air in from the 80mms. You also will be having the hot air being pulled down and out from the back, preventing it from naturally rising, therefore heating your case when it doesn't have to.

[aston]

This is spooky: You seem to have (mostly) the exact same hardware that I'm using.

...
2 optical drives, Plextor cd-burner + LG dvd-burner
...

Wow, how did you know I have a Plextor too? (Actually, mine is an ancient 40x SCSI CD-ROM... I think it's actually time to retire it.)

I wanted to stop the psu from ramping up so I wanted to duct it to the top front-bay. But I also wanted to have an exhaust-fan as high in the case as possible and preferably exhausting up (like in your setup). Therefore I moved the PSU as far forward and upward in the case as possible and made some brackets to keep it there.

So let me get this straight: your PSU is in the middle of your case? How do you reach the on/off switch then?

While the flipped PSU idea is good, i still think that your overall airflow plan still needs to be revised. Use the top 120mm to blow air out, and the other 2 80mms to blow air in. That way, fresh, COLD air reaches the CPU, graphics card, etc, and then as it carries away the heat, which, NATURALLY RISES, can be sucked out before it heats up other components.

Yeah, I just thought about that too, after I read a thread here about building a chimney. I think you're right -- might as well take advantage of the fact that hot air rises.

At the same time, I think I should reverse the PSU fan so that it blows up as well. If Neil is right -- it's easier to pull air than push it -- then theoretically it should be better to pull air out of the PSU than push air into it. The air should rush in to fill the PSU compartment through the back if I have the fan blowing out the top.

This would have the added benefit of overall airflow going in the same direction. (PSU airflow going from back of the case to the top, and case airflow going from back to top as well.) I'm guessing there will be less recycling of hot air this way.

[acaurora]

Actually I am beginning to want to retract my statement that the reversed PSU idea is a good idea. Chances are that the hot air will still reach your PSU, and, instead of getting sucked into it, it will just heat the metal casing of the PSU while being sucked toward the middle to be blown out. If you do decide to do this, might I recommend a solution:

1. Create some sort of directional air guide to the center or to the fan. Maybe a very thin piece of aluminum, held by screws. I dont know specifically how to do / make one, I'm sure someone else here can help you out with creating that sort of duct. That way the heat does not reach the PSU, preventing any damage. As a bonus, the hot air will *rub*, if i may say, against this piece of metal / non-heat conducting material and will keep it cool instead of constantly heating it up. IN addition, it will help get the air out faster. Perhaps acrylic or some other type of material that resists heat would be a better replacement.

2. If you don't want to go that route, then you probably are better off leaving your PSU as it is, to help bring out the air. If you flipped it, and without the duct, you're going to have one sizzling PSU -.-;;

[aston]

As long as I have proper airflow in the case, I don't think the hot air will heat up the casing of the PSU... and even if it did, I doubt that it'd be a big problem. It's really no different than building an air channel for the PSU as others here have done, right?

I also plan on leaving the stock thermisistor-controlled fan in the PSU for as long as possible so I can verify that the fan doesn't ramp up. I think it's a good gauge of how cool the PSU is running.

As for ducting, maybe one day I'll be crazy enough to attempt it. But right now I'm happy with the temps and the amount of noise my Zalman 7000AlCu makes.