Optimizing case airflow

JEN · Post by **JEN** » Mon Apr 21, 2003 12:50 pm

Hi everyone!

I am fairly new to computer cooling and have a question!

What would be better?

1. modding the PSU with 2 silent 80mm fans + 1 silent 92mm side intake fan?

or

2. modding the PSU with 1 silent 80mm fan + 1 silent 92mm side intake fan + 1 silent 92mm top-of-case exhaust fan?

powergyoza · Post by **powergyoza** » Mon Apr 21, 2003 1:23 pm

JEN wrote: 1. modding the PSU with 2 silent 80mm fans + 1 silent 92mm side intake fan?

or

2. modding the PSU with 1 silent 80mm fan + 1 silent 92mm side intake fan + 1 silent 92mm top-of-case exhaust fan?

Hello Jen,

Neither is ideal, but if those were your only choices, I'd go for #1. If you can, remove 1 fan from the PSU.

Top-of-case vents/blowholes do not make any sense for most case setups. Your CPU is too far away from the blowhole to make any difference.

In general, the best setup (IMO) is to have 1 fan in the PSU and 1 - 2 exhaust fans in the back near the CPU. For the intake side, my ideal would be good open vents, but no fans, somewhere in the bottom/front quadrant of the case.

rpc180 · Post by **rpc180** » Mon Apr 21, 2003 1:31 pm

hey, welcome to the forums,

You'll get quieter cooling if you only leave 1 fan in the PSU. Question is if the PSU can handle just 1 fan. If its already got 2 fans in it, 1 low speed fan might be pushing the envelope alot (because the 2 stock fans are usually medium speed fans though thermally controlled, will still push more air then a single low speed fan by several multiples).

As for side intakes, they do bring down internal case temperatures a little, but they deffinately add to noise because they're mounted to a big flat peice of metal (or plexi), that transmits vibration alot. Most will usually get a duct for passive airflow, usually as effective. I'm actually toying with the idea of cutting a window in the side of the case and leaving it open with no plexi in the way. Quieter than fans and just as effective. My comp's on a shelf though, so I don't really need it protected, but maybe some chain link fence or so would suffice for some protection.

As for top casefans, most say that they are unnecessary and case temperatures don't get affected too much with a chimmney fan.

JEN · Post by **JEN** » Mon Apr 21, 2003 2:16 pm

Thanks for the replies, and thanks for the warm welcome

OK, so the top-of-case fan idea is out the window

I have been thinking about the intake fans being at the rear of the pc, but the problem is that I have one of them flower heat sink fans, so if I added intake fans to the rear, they would be blowing air at the heatsink fan which would cause it to make more noice! A fan blowing at another fan is not supposed to be a good think! is it?

The current situation:

On a cool day, the CPU is @ 50C and the HDD is also at 50C!
On a warm day, the CPU is @ 55 to 60 and the HDD is 56+!!!

The HDD temp is not good is it! It is so high because its in a Silent Drive Encloser by QuietPC

So, how do I get the temperatures down while keeping the computer virtually silent without cutting holes which will not be covered with anything?

About the PSU, it has only 1 fan originally! I wanted to add 2 quiet 80mm fans running at there slowest. Is that not going to cool it quietly?

Post by **MikeC** » Mon Apr 21, 2003 2:39 pm

Jen, your thread has been moved to cases & damping, which is more appropriate.

The info about temps is not useful to us till we know full details of yoru system + the ambient temperature in your room. But generally, most CPUs run fine to 70C+ & don't burn till 90C. Silencers tend to push the temp envelope.

Tell us your details so we're not groping in the dark.

powergyoza · Post by **powergyoza** » Mon Apr 21, 2003 3:53 pm

JEN wrote:I have been thinking about the intake fans being at the rear of the pc, but the problem is that I have one of them flower heat sink fans, so if I added intake fans to the rear, they would be blowing air at the heatsink fan which would cause it to make more noice! A fan blowing at another fan is not supposed to be a good think! is it?

[snip]

About the PSU, it has only 1 fan originally! I wanted to add 2 quiet 80mm fans running at there slowest. Is that not going to cool it quietly?

Jen,

I've bolded the part of your above msg that seems to be the problem with your case. The fan at the rear is not supposed to be intake. It's supposed to be exhaust!

2 fans in a PSU may cool it a little better, but at the expense of more air noise, compounded by extra turbulent noise. You're better off staying with 1 fan and making the vent in the PSU less restrictive.

Cheers!

Post by **MikeC** » Mon Apr 21, 2003 4:00 pm

oh, a silent drive! missed that on the first read: get it out of there! they cook drives. Really. See the reference in the recommended hard drives (on main site).

powergyoza · Post by **powergyoza** » Mon Apr 21, 2003 4:03 pm

Thanks for catching that mike. SilentDrive has gotta go.

JEN · Post by **JEN** » Tue Apr 22, 2003 12:39 am

Putting the Silent Drive Enclosure aside for a moment, after reading all the posts, I think I should do the following:

PSU - Replace fan with 1 quiet fan, cut big holes for better ventilation,

CPU - Leave as it is (flower heatsink + 92mm fan) and make a duct for it,

Case air flow - Make 1 hole at the bottom with no fan and add 2 80mm silent fans at rear of pc as exhausts

GPU - Get the VGA fanless heatpipe

Questions:

1. would it be better to cut 80mm holes in the front and rear of the PSU and mount 1 silent fan externally?

2. I went to the local hardware store, but could not find any appropriately sized pipes for the duct, they only had 110mm and 68mm, what can I do about this?

3. How big should I make the fanless side intake hole, I’m thinking 92mm, would that be enough?

[edit] typos... [/edit]

Post by **MikeC** » Tue Apr 22, 2003 1:09 am

Jen, you really should list / name your components. You would also do well to read the project articles in the Systems section of the main site.

PSU - Replace fan with 1 quiet fan, cut big holes for better ventilation, -- where, why? Only thing recommended is to cut away a stamped out grill on the fan exhaust hole, and turn the metal between the slot holes on the intake side 90 degree. See powergyoza's PSU intake side pic in his quiet dual mp sustem article.

CPU - Leave as it is (flower heatsink + 92mm fan) and make a duct for it, -- may not need a duct if you have a back panel exhaust fan on a unrestricted hole.

Case air flow - Make 1 hole at the bottom with no fan and add 2 80mm silent fans at rear of pc as exhausts -- just enlarge / remove the grill from front panel (low) intake hole.

GPU - Get the VGA fanless heatpipe -- may not be enough fanless; may still need a 80mm fan (Panaflo 80L at 6-8V), but this fan by itself may be enough, so get this first...

1. would it be better to cut 80mm holes in the front and rear of the PSU and mount 1 silent fan externally? see above

2. I went to the local hardware store, but could not find any appropriately sized pipes for the duct, they only had 110mm and 68mm, what can I do about this? see above

3. How big should I make the fanless side intake hole, I’m thinking 92mm, would that be enough? don't do a side hole, more noise will escape. I block the ones on my cases -- and my best system runs cool at ~10 dBA

JEN · Post by **JEN** » Tue Apr 22, 2003 12:53 pm

Case air flow - Make 1 hole at the bottom with no fan and add 2 80mm silent fans at rear of pc as exhausts -- just enlarge / remove the grill from front panel (low) intake hole.

I can't cut out a hole at the front of the case because that's where the usb and power switch are located. That is why I thought of making the side hole! Any ideas?

GamingGod · Post by **GamingGod** » Wed Apr 23, 2003 5:53 am

Do you have a picture of your case? Also you can always consider a bottom intake. But you may want to change the rubber feet on the case for taller ones for better airflow. Or just put casters or something to raise the case up a bit.

JEN · Post by **JEN** » Wed Apr 23, 2003 7:10 am

GamingGod wrote:Do you have a picture of your case? Also you can always consider a bottom intake. But you may want to change the rubber feet on the case for taller ones for better airflow. Or just put casters or something to raise the case up a bit.

Picture of my case is here. Please don't laugh, I bought it for £5 from a computer fair!

Where can I get something to raise the case but keep it stable at the same time?

GamingGod · Post by **GamingGod** » Wed Apr 23, 2003 9:23 am

cant get your link to work, so ill wait till you get the link fixed before I laugh at it. If your considering putting in a bottom intake, then you could either replace the rubber or plastic feet with some that you find at a hardware store or possibly walmart. Ive seen rubber feet that were 2" tall before. I dont know what your case looks like or where you usually have it sitting (on the floor, on a desk?) so I dont know what would be the best thing to use as a coaster. But im sure you can think of something inventive if you just look around the house for a second. Maybe little blocks of wood, or maybe actually coasters like you could put under a drink?

JEN · Post by **JEN** » Wed Apr 23, 2003 9:54 am

GamingGod wrote:cant get your link to work, so ill wait till you get the link fixed before I laugh at it. If your considering putting in a bottom intake, then you could either replace the rubber or plastic feet with some that you find at a hardware store or possibly walmart. Ive seen rubber feet that were 2" tall before. I dont know what your case looks like or where you usually have it sitting (on the floor, on a desk?) so I dont know what would be the best thing to use as a coaster. But im sure you can think of something inventive if you just look around the house for a second. Maybe little blocks of wood, or maybe actually coasters like you could put under a drink?

I have updated the link, it should work now (I hope!). You will not be able to see this from the picture, but I keep the case on the table, so dust is not a major issue.

Anyway, have a look at the picture, and please, try not to laugh to much

Post by **MikeC** » Wed Apr 23, 2003 10:27 am

yeah, those bottom front panel USB/other in/out panels are just terrible for airflow. A bottom panel 80-92mm hole near the front should work nicely with 1" tall rubber feet and bug netting filter. Only add an intake fan if temps are still too high. You can find rubber feet at all kinds of hardware/furniture stores. And electronic supply stores.

What's to laugh, btw. A case is a case.... but is that a Vantec fan contoller I see there? They had a serious buzzing problem when the speed was turned down -- how is yours?

JEN · Post by **JEN** » Wed Apr 23, 2003 10:37 am

Yes, the fan controller does have a buzzing problem when all fans are turned down! Im thinking about giving it back, is there something I can do to it so I don't have to give it back?

Post by **MikeC** » Wed Apr 23, 2003 10:45 am

Apparently not. It's a design flaw. I have samples of both the cheap Sunbeam fan controller (looks very similar) and the not so cheap Zalman; both work fine, the Zalman is nicer in some ways but only goes to 5V, while the Sunbeam goes from off to 12V -- but has super brihgt annoying lights -- which you can fix by bending them in...

GamingGod · Post by **GamingGod** » Wed Apr 23, 2003 11:40 am

Are those holes in the side of the case? If so you might want to tape over them in the inside so that the noise cant escape as easily. And whats the new plan now Jen? a hole in the bottom for intake, and a fan or two under the power supply for exhaust?

JEN · Post by **JEN** » Wed Apr 23, 2003 1:51 pm

Yes, they are holes in the case!

Plan 4? or is it 5

Hole at bottom of case, would it be anygood to duct it towards the HDD?
2x 80mm silent fans at rear, maybe externally
replace PSU fan with 1x 80mm silent fan, maybe externally
duct tape all other case holes and gaps
larger rubber feet to raise the case

have I missed anything

Post by **MikeC** » Wed Apr 23, 2003 2:11 pm

Sounds good, but just start with 1 80mm back panel fan. add 2nd only if necessary, and cut away any grill restriction for the fans. Look around for decouple-mounting techniques for fans. Powergyoza has some dandies in his quiet dualie article on the main site under systems. This makes a difference. Play with ducting only after you have the basic setup going, you may want more of the fresh air going to the CPU area, as HDDs don't usually get that hot.

dukla2000 · Post by **dukla2000** » Wed Apr 23, 2003 2:38 pm

My 6p.

The advice to set the rear fan as extract (plus air exhausting from the psu) is good. The real problem is you need to get air entering the case somewhere. On that case you may have some holes in the tin behind the USB stuff? If so, you probably have some pitiful 'slot' at the bottom edge of the blue (under the USB)? If so, make that slot as big as possible (with a Stanley knife) and even hack away the tin so you have a nice 80mm diameter hole instead of a pretty pattern of small holes.

Second option (mentioned above): make a hole in the front floor of the case (and maybe mount a fan sucking air of the floor of th room). And to raise the case, get some caster wheels and epoxy them on. I did: raises the case 2" but more important makes it easy to push around.

If you have 1 case fan exhausting, the psu fan exhausting plus the equivalent of 2 fans holes for air to get in, you should be OK.

ps - I wouldnt close any of those side holes until you have your airflow and temps under control, and even then I would tend to leave them myself.

Riffer · Post by **Riffer** » Wed Apr 23, 2003 4:24 pm

Any pics of the inside?

GamingGod · Post by **GamingGod** » Wed Apr 23, 2003 4:35 pm

Closing the side holes will cut down on the noise that exits the system. Also I dont think that you need to mount the rear exhaust fans externally, that is only useful in power supplies because its a tight space and it can cut down on the turbulence in the power supply.

JEN · Post by **JEN** » Thu Apr 24, 2003 12:16 am

Went to the local hardware store yesterday to get a 80mm drill saw. The largestdrill saw they had was 62mm. How can I make a (not to scruffy) 80mm hole in the case without too much effort?

dukla2000 · Post by **dukla2000** » Thu Apr 24, 2003 1:03 am

Tin Snips - see the post here http://forums.silentpcreview.com/viewtopic.php?t=2307

Actually I use garden secatuers

, I also have a nibbler (cost £20, better for straight lines than curves) and a grinding wheel in my drill to do the final tidy up. If you go to a specialist harware store you can find hole cutters up to and beyond 120mm, but they cost a fortune (like £40) which is hard to justify for 1 or 2 holes.

Post by **MikeC** » Thu Apr 24, 2003 1:06 am

Cutting holes -- I've used a jigsaw w/ metal cutting blade, mostly, and it makes for pretty rough cuts, but there are little soft plastic edge covering thingies you can use... Then there's tin snips, which I will have to try, after studying crisspy's great post about this again: http://forums.silentpcreview.com/viewtopic.php?t=2307

rpc180 · Post by **rpc180** » Thu Apr 24, 2003 7:16 am

Home Depot and Lowes around here carry hole saws in 3" diameters. This approximates 80mm pretty well. 3.25" is pretty much perfect. They're costly though, like $20 or more for 'em but they make pretty much perfect cuts.

JEN · Post by **JEN** » Fri Apr 25, 2003 9:59 am

I am almost done modding! I got 1 exhaust fan at the back, under the PSU, I replaced the PSU fan for a silent fan, and also decoupled the HDD with 1m of clothing elastic (only 25p!). Now I only have 2 more things to do:

1. Cut an 80mm intake hole at the front-bottom - I am finding this a bit difficult as the local hardware store does not have any Drill saws or Tin snips??? The local hardware store is B&Q. It is not a specialist hardware store, but a general purpose hardware store.

2. Cover all other holes with duct-tape - That should be easy (I hope

)

dukla2000 · Post by **dukla2000** » Fri Apr 25, 2003 2:50 pm

JEN wrote:I am almost done modding! I got 1 exhaust fan at the back, under the PSU, I replaced the PSU fan for a silent fan, and also decoupled the HDD with 1m of clothing elastic (only 25p!). Now I only have 2 more things to do:

1. Cut an 80mm intake hole at the front-bottom - I am finding this a bit difficult as the local hardware store does not have any Drill saws or Tin snips??? The local hardware store is B&Q. It is not a specialist hardware store, but a general purpose hardware store.

2. Cover all other holes with duct-tape - That should be easy (I hope )

And how is it sounding, and how are the temps?

For 1: If you have a dream to oneday put a fan there then maybe this isn't the best advice. Otherwise go back to B&Q, get some £4.97garden secateurs and go for it - the hole can be square (or kind of funny shaped because it is your first!) and not make any difference as it is out of sight.
(Actually they really should have £4.98 tin snips - see www.diy.com. Not exactly the standard crisspy would expect but needs must ...)

BTW - your rear case fan & psu fan - do they have stamped cut-outs or wire grills? If stamped cut-outs, use the tin snips/secateurs to remove them as well.

Optimizing case airflow

Optimizing case airflow

Re: Optimizing case airflow