Case airflow design opinions?

[macklin01]

Hello, all!

I'm about to start modding a brand new AMS Gmono with side window like here. (More pics here.)

Here's what's going in it:

1) P4 3.0C @ 3.5 GHz with SP-94 and 92mm Panaflo M.
2) 3 x 512 MB Kingmax PC3500 (eventually will be 4x512 MB)
3) Abit GF4 Ti4200 with Zalman passive cooler.
4) Abit AI7 mobo with stock NB cooler
5) Antec 430W TruePower
6) WD 7200RPM 80GB Special Edition
7) Samsung CDRW/DVD combo drive
8) Creative SBlive! 5.1
9) 1-2 12" cold cathode tubes, like this one. (I like the idea of the subtle, rippling water effect inside. To come to think of it, that would be pretty cool with water cooling...

I'd like to mod it for quiet cooling that compromises neither aesthetics nor performance.

Here's what the case currently has for cooling:

1) 1x120mm front intake, with extremely restricted airflow.
2) 2x80mm rear exhausts.

Here are some mods I'm currently considering:

1) Drilling a 80mm, 92mm, or 120mm hole through the acrylic side panel for a direct intake for the CPU / gfx card area. Preferred size is 92mm, of those.

2) Drilling a 80mm, 92mm, or 120mm blow hole through the top for exhaust. Probably 92mm or 120mm of those, most likely 92mm, since I'd prefer to not need 2 expensive hole saws.

3) Of course, removing all the punched fan holes and replacing with less restrictive fan grills.

4) Replacing the case feet with slightly taller, rubbery case feet, and adding a bottom air intake. (Since the front intake probably won't do much.) 92mm or 120mm size in that case.)

General flow diagram would be something like this.

For 80mm fans, I'll be using 80mm Panaflo L's. For 92mm fans, Panaflo L's or Zalmans. For 120mm, certainly Panaflo L's.

Any advice for me? In particular, I've never added a top blow hole, so I'm uncertain on how it would contribute to improved cooling. Thanks! -- Paul

 

[rogerdugans]

Biggest problem I see with that setup is the airflow pattern with the blowhole so close to the front- the one time I tried that I had worse temps.
In the small case I had at the time, I found that an Intake in the top of the 5 1/4 worked better- I used an 80mm and two 5 1/4 slots, although I suspect you won't have the free bays to do that.
As an experiment to SEE if that blowhole would work without having to mod the case, you could leave two bays free and put an exhaust fan there- similar airflow pattern.

The other thing I see right off is the location of the side fan- I'd drop it down a bit to guarantee some airflow under the agp card- that tends to be a dead area unless you use a slot fan.

 

[macklin01]

Thanks for your post!

Interesting ideas!

That's definitely why I wanted to ask about the blowhole. I like your idea to experiment with it. Only difficulty for me is that I hoped to fully plan the mod before installing components, since the case is brand new and easy to mod at the moment. Perhaps a two-tiered approach is best, however: simple mods now, more later if necessary ...

Right now, I'm thinking that I should use the two exhausts at 5V and some sort of side intake. I'm unsure as to its placement. It would be nice to directly duct to the CPU, but your point about the AGP area is a very good one. I hadn't given that much consideration ...

What do you think about a bottom fan mount? How about the front intake? In general, I've found the front intake on most cases to be pretty useless, generally ...

Thanks again! -- Paul

 

[navicaph]

You could try intakes at the bottom of the case. I have one 80mm and its lowered the temps in my case. Just remember to add a filter to it if you do.

 

[rogerdugans]

Two tiered approach is DEFINITELY the way to go, imAo.

At least half the great ideas I've had had been completely wrong- if I do my cooling mods FIRST then I am stuck with a horrible machine.

My favorite cooling mod tool: cardboard.
Makes great temporary panels for finding the best fan placements and when you do find what works you also have a template for use in cutting the real parts out.

Intake location:
I have never tried a bottom intake, but I have heard great things- as long as there is a decent amount of room underneath; an inch or so would be good, I think. (Theory anyway- see above comment about how my theories often work out.)
I have had very good success with front intakes- as long as ALL obstruction is removed. For best results, even the bezel is modded with a fan grill for a completely open air intake. Its amazing how much just having a closed bezel restricts flow, even if there is plenty of space under/around it.

Voltages:
I have used 5volted fans, but many need more voltage just to start; 7 volts is usually just about as quiet and sufficient to start most 12v fans.
If you have one, or can afford to get one for testing..or can fit one in the system...
a multi-fan controller may be your BEST friend:
you can adjust voltages for optimum flow and noise.

My main H2O rig runs with the best compromise of noise/performance with my intake (rad) at about 7 volts and exhaust approximately 8. Running both at the same voltage increases case temps about 2c on average.

Even if you just use a controller (available for less than $20 USD often) for testing and then determine voltages and resistors needed to set fans at those speeds permanently, you may get better results for what you want.

 

[macklin01]

Thanks both for the additional feedback.

Actually, I do have a multichannel fan controller. (self-designed, too. ) I plan on completely removing that and temporarily running at full speeds while retooling it a bit, in the meantime. Here's the design, per channel:

http://www.math.umn.edu/~macklin/fanbus/basic_design.gif

Runs 7V to just under 12V, with a bypass to full 12V. (The zener diode ensures that the voltage across the transistor doesn't drop too low.) In my retooling, I'd like to reduce the Ohm rating of the variable resistors, fix some bad solder joints, change one of the channels to control the cold cathode, and probably remove the relays, as my current mobo doesn't turn off fan headers during standby anyway.

I'm starting to think more seriously about the bottom intake with new case feet. Nice thing about that is that if I decide I'd rather not use it, I can always plug the hole with a sheet of steel or aluminum and nobody will ever know the difference.

I've also floated some ideas as silentpcreview, but they seem to have digressed into ditching case intakes, letting exhausts naturally draw air, ditching my 92mm fan on the HS, ... (I think they've lost sight of the fact that I'm not looking for silent cooling, but rather moderately quiet cooling with good performance )

Thanks again. Please keep the great ideas running! -- Paul

 

[rogerdugans]

I have had some good luck with passive intake- but ONLY in a very large case where natural airflow has plenty of room.
And the cooling perfomance is just NOT up to snuff when compared to Active Intake.

I'm interested in hearing how you do with a bottom intake- one of the few things I have NOT tried.....yet.

 

[macklin01]

Tempted to try a hole in my current case (Since I don't care about it anyhow) to see how it works. Except that I'm not feeling like removing the guts to drill the hole ...

Actually, I agree about passive intake, the more I think about it ...

I'm starting to move in the direction of a passive side panel duct to the HSF and a bottom intake at low voltage to give just enough fresh airflow for the vid card. I've pretty much ditched the idea of a top blowhole for the time being ...

Hmm, looking for an easy way to get that bottom intake ... -- Paul

 

[macklin01]

Wow, this looks pretty cool!

http://www.overclockersclub.com/guides/fanduct.php

 

[AFIsoldier]

Here is my suggestion (note that I am a soul believer of positive pressure reigning supreme), Add a 92mm to the bottom as intake, 92mm top exhaust blowhole, reverse rear exhaust fans to intakes, 92mm blowhole intake on side.

This will force all hot air to leave the top, the rear intakes will blow fresh air onto the heatsink from the left, the side blowhole will push air straight on, the 120mm will force air in to the bottom and right side of the heatsink, the 92mm bottom blowhole will blow air across the vidcard, mobo, and push air into the bottom of the heatsink.

Hot air will rise and leave the case from the top allowing fresh air to accomodate 80% of the case.

Check out my thread "5x intake, 2x exhaust?". I have seen temp drops of 2-3ºC just by reversing the rear exhaust fans.

Good luck, go ahead and add the three blow holes (I suggest all 92mm), and you will see noticeable drops in temps.

 

[rogerdugans]

While I have always had much better luck with negative ventilation, I must say that AFIsoldier's idea sounds like a good one.
I won't even GUESS what will work better, but going to that extreme with Intake/Exhaust ratio may work; I've stuck fairly close to a balanced system for most of my systems.

The plexi duct: I tried a few ghetto versions along those lines- mine always ended up interfering with case flow too much though, and I never found a way to implement without killing my case temps. Of course, I probably gave up far too easily.

 

[magick_man]

ok i have just made up some ideas on inventor and posted the pictures on my site

http://www.msnusers.com/picturesofshiot/shoebox.msnw

they are the 3 on the bottom
"macklin01-case-1" through 3

and for the lights i suggest these

http://www.compusa.com/products/product_info.asp?product_code=306886&pfp=cat3

dual blue clod cathode 12" sticks for 20$
i have them in my case right now and they are bright

Magick_Man

 

[AFIsoldier]

Your idea is flawed, in a sence.

If one rear fan is exhaust, and the other intake, all the intake will do is suck in hot air.

He already has a 120mm in front, no point in adding 2 noisy 80mms.

Good diagram, and it was a great attempt. Use what I have told you and figure something out, because this should be a group effort to help macklin get the most out of his case.

 

[AFIsoldier]

Seeing as you only have 1x hdd, I would remove the hdd cage and place your hdd in the floppy bay. I plan on doing that to make room for a heatercore and to increase flow for the time being.

Take a dremel or some tin snips to those fan grills, they look more restrictive then...well, forget the analigies.

After you have those grills out of the way, time to attack the front bezel of that case. It apears to be a piece of lexan over a sheetof alum. Am I correct in that?

If you have a dremel, this will be easy as poo. If you only have a power drill, it will take more time but still be fairly easy.

If you have a dremel, then just cut slits straight down the bezel infront of the 120mm. If you have only a drill, then drill holes in the bezel in whatever pattern you wish, just try and get it as in restrictive as possible.

Be VERY careful when drilling/cutting the lexan and take your time as not to crack it. I would recomend taking the lexan and metal apart and doing them seperatly, but be sure that your cuts/holes line up so it looks real nice.

Good luck, I am still checking out the case and will probably recomend some more ideas on cooling that machine.

 

[Tango57]

my Lian Li PC-60 came with a blowhole on top, right in the center so i mounted an 80 mm exhaust fan with a cold cathode grill, but to be honest i haven't really noticed any temperature drop or difference in my setup. it just looks cool with light coming through the top grill. i would also suggest mounting the side intake just below or at the level of the agp card to give it some more airflow there.

 

[magick_man]

AFIsoldier i see your point so i have made changes to my pictures and re-posted them on my site
http://www.msnusers.com/picturesofshiot/shoebox.msnw?Page=1
the bottom 3
"new Macklin01 case 1" through 3
for some reason the thumbnails arent working right now but hopefully soon

i think this idea should be better

Magick_Man

 

[macklin01]

Wow, thanks for all the ideas, folks!

Impressive images, btw! What software did you use for that? I've been toying with putting something in a freeware CAD package, but I haven't had the time ...

About the hdd: I feel that putting it in a floppy bay will accumulate too much heat for it. I did consider cutting out that bottom drive portion to make more room. Certainly not too much for my dremel with tungsten carbit bit and a bit of sanding.

About the front panel: it's acrylic, and I'd really like to avoid cutting it if possible. (It looks so nice!) But it's definitely an idea worth entertaining. I'll certainly agree with that.

I had indeed considered using rear 80mm's as intakes. That might be a nice way to avoid the side intake in the acrylic.

Interesting ideas, everyone! And very impressive. Thank you so much! -- Paul

 

[magick_man]

i have the full version of autocad's inventor 7 software it is pretty cool once you get the hang of it
i got it from the H.E.B. tech center that i go to
my teachers are cool and i am like the only person in the class that can really use it (including the teachers)so they let me have a copy

Thnx, Magick_Man

 

[macklin01]

Hello, all!

Thanks again for all the input. I thought I'd give a little input on where I am with this. I'll break it all down into several points with reasoning ...

1) Top blow hole: because opinions were so mixed on the benefits of a top blowhole, I decided to take a wait and see approach. Now that the whole system is set up, when I feel the top steel of the case, it is indeed the hottest part of the case, so some heat seems to be accumulating. Perhaps this is a situation where a top blow hole will help. I'm still going to wait and see on this one.

2) Bottom intake. I came very close to doing one of these, mostly to direct some fresh air towards the AGP card and HSF / NB area without a side intake. But then I realized that my sound card would block a lot of that air. Furthermore, the consensus I've seen (and I agree with) is that exhausts will provide a natural draw through the intakes, so intake fans aren't necesszary except when directed spot cooling is desired. However, I may add a passive bottom intake with a filter in the hopes of controlling dust and inproving natural airflow patterns.

3) Side intake. I decided to wait this out to see how the current cooling does. If I decide to do it, I'll probably go in two steps: first, experiment via cardboard to find the ideal placement and use a simple passive duct. Then, if need be, add a slow fan. The duct would be 92mm.

4) Exhausts. For now, I have 2 panaflo L's running at full speed in the typical exhaust positions running as exhaust. They seem to do the trick pretty well, as the system temps are comparable to my previous case that had one exhaust and one side intake directly above the HSF. I cut the punch metal grating out and replaced with wire grills.

5) Fan controller. Eventually, I'll be redesigning my custom fan controller, although the temptation is high to just buy one, since they're so cheap now ....

6) Front intake. Right now, there's no fan there, although I cut out the punch metal grating out in case I ever want to use it. That should help for passive intake as well. I may add a slow 80mm or 120mm fan there to slightly cool the hdd.

7) Cabling. I used spiral wrap as can be found in another thread here with good success. I also managed to hide a lot of the cables against the non-window side panel.

8) Cold cathod tube. I got the liquid cathode I mentioned above, and while it's cool, it's not quite as bright as I had hoped. Also, because it's a pretty fat tube, I can't hide it out of direct view to get the effect I wanted. (I want to light the interior without looking directly into the lights, and I had hoped to observe a shimmering, wavelike effect.) I'm looking at meteor LED lights (a 12" row of LED's in a plastic housing) or dual cold cathodes. I'd need something with mounting hardware that's no bigger than about a centimeter. Any suggestions? Also, any impressions on LED-based lighting?

9) Power Supply Duct: This is a cool idea from spcr. In essence, you duct the PSU intakes to the outside / top of the case to get cool air. The PSU runs cooler, and thereby quieter. Of course, to do this properly, I'd assume that case exhaust would have to be all the more efficient. An interesting idea, but one that I'm holding off on, as the PSU is not the loudest element.

10) NB cooling: For now, I removed the stock sink and reapplied AS3. (Not worth using the AS5.) I'm definitely looking at replacing it with something passive. I wish there were an easy / good way to mount the Zalman NB sink without adhesive ... From what I've read and seen, passive cooling should be more than sufficient.

Thanks for all the help! I'll be continuing to look at your suggestions and implement them in the near- and long-term future! -- Paul

 

[syberspy9]

IMO i would mount
1 120mm front
1 120mm rear
1 120mm side (line the center of the fan with the vga card so it will blow cool air in the middle on the vga card,and bit on the cpu and NB )
1 92mm top blow hole
and a dual fan psu


the reason im all for 120 is because when hooked up to a fan controller you can run them with little noise and they will still push out the cmf's
as fot the 92mm top you could put a 120mm there in place also i just though a 92mm wouild fit better