Is a 120mm top blowhole worthwhile?

[Flarkit]

Hi

I've bought a Beantech Igloo 1 (link), which is essentially a knock-off of the Lian Li PC-65. I'm after cool and quiet, so I'm removing the standard 80mm fans (2 front, 1 rear).

I've simply removed the 2 front fans, leaving a big intake hole with the nice standard filter. I've also enlarged the rear 80mm fan's spot, in preparation for a 92mm Vantec Stealth.

Then I'll make a top blowhole for a 120mm Vantec Thermoflow. However, I've seen mention of this actually causing warm air to circulate?!?


Also thinking of ways to ensure that the big hole doesn't become a serious dust intake (mostly when the PC's off, I assume). I might simply put a filter or cover and manually close the hole when I shutdown. Or look for a light material that the fan would lift when it's blowing.

[BigDov]

I suppose it could circulate warm air as you say (drawing it to the top of the case) but that's the natural way for that air to go anyway.

[Flarkit]

Originally Posted by BigDov

I suppose it could circulate warm air as you say (drawing it to the top of the case) but that's the natural way for that air to go anyway.

Hi

I fear that by having no intake fans pushing air into the case, perhaps the 3 exhaust fans (the PSU fan + a 92 mm rear fan + the 120mm blowhole fan), may cause a vacuum effect to start pulling air back through the 120mm.

This is affected by having the 2 front 80mm openings covered by a filter, which may:

a) drastically reduce the air that could flow in there

b) force air to be sucked in through other openings (eek!)

[danrok]

With no intakes you'll most likely see more dust building up inside you case.

[cloasters]

My B Box has a 87 cfm 120mm fan drawing air in. The 80mm 38 cfm fan in the upper rear of the case pushes air out of the box, plus the power supply's fan and a 92mm 45 cfm blowhole fan on the top of the case. Intake and out-flow values are close, but out-flow is more than the intake when you add the PSU's fan to the mix. This is not ideal. It's said that a slight overpressure in the case is best. For example, 90 cfm in and 80 cfm out. This helps keep dust out. The 92mm blowhole fan doesn't let much dust into the case when it's not running. But I cover the blow hole when the machine isn't running and I wait until it's cool before putting on the cover.

Fans that blow air out of the case shouldn't be filtered.

[Flarkit]

Originally Posted by danrok

With no intakes you'll most likely see more dust building up inside you case.

And with (filtered) intakes, I will hear more noise, right? So it becomes a tossup between noise vs dust then? That is, without even factoring in the effects on cooling.

[Renasc]

A low-reving 120mm blowhole would be ample (even a low-reving 80mm would be fine). I'd recommend sealing your case up, so that air can "only" enter the case via the dust-filter.

[cloasters]

I think that this case needs an intake fan. Adding another exhaust fan right now is a waste of time and effort. A slow-turning 120mm won't be loud. If a 120mm fan can't be mounted in the lower front of the case, a hole can be cut into the lower half of the left case cover. Plan this hole carefully, the interior fan mount can't bump into the drive supports in the front of the case, or the PCI cards in the rear of the case.

Any holes in the front of the case should be sealed after installing a 120mm intake fan. They don't help!

[weldzilla]

Your over thinking this!!! Good grief. you say you are after cool and quiet. Well what is your interpretation of cool? What is your interpretation of quiet? If you want all these exhaust fans but no intakes. I got news for you. This is a waste of fans. The way you want to run your blowhole fan is not logical. What woulf make you think that every bit of dust in your house is going to find it's way to your blow-hole opening? When you are shutdown. If you are so concerned cover it. This is just a little too over the top for me.

To answer the question you asked at the start of this thread... YES

WZ

[Flarkit]

I do tend to over-think things. Being cautious that way usually means I come to logical conclusions.

"Cool", for me implies that the case's temperature stays below 30degC, which in turn should mean that the CPU doesn't go much over 45degC under load. It's winter here currently, so this is easily achieved. In summer, the external temperatures can reach 30degC, which I'm wary of.

"Quiet" for me means only just detecting sounds coming from my PC (including fans, hard-disk and vibrations), preferable as a soft hum. Sorry I can't be more scientific than that.

Why is it illogical to have a blowhole, exhausting warm air from the top area of the case?

[Flarkit]

The work's done on my case and I've just completed installing my components into the new aluminium case and it's working pretty decently (pics to follow). I added a 120mm blowhole and removed the 2 front 80mm fans, leaving just the filtered spaces. I also tried my hand at routing the cables behind the motherboard tray, with moderate success.

The main issues I'm facing are:

- I'd like to seal off the panel behind the front bezel, as well as the edges of the side panels, to prevent dust from coming in everywhere. Which material is recommendable, cheap(!) and common?

- I struggled a bit with the cabling. I have most of the wiring passing along the side of the case which the motherboard is on. A large bunch, including 2 rounded IDE cables and 2 PSU wires are practically dumped in the gap formed between the 3.5 bracket and the side panel. This is not perfect, since it presses against the side panel and seems untidy.

- I was excited to see that I could get the wire for my Radeon card to run behind the tray and then pass through a mounting hole in the motherboard at the point where the gfx card is screwed to its rear slot. Unfortunately, that hole is only just big enough to tightly squeeze the 4 wires through. This caused chafing and a very small amount of the red plastic was scraped.

Enclosing the wires in a heatshrink tube won't fit through the hole. This means having to pass the wire along the front edge of the motherboard, cable-tying the wire in place and then running a bit past the end of my RAM to the gfx card. Not optimal, IMO.

Any suggestions to improve things a little more would be most appreciated

(hope this is the right place to ask)

[Flarkit]

PICS:
(apologies for grainy cell-phone camera quality)

1) This shows the motherboard power-cable, which passes the RAM. It also shows the gfx card's power. The IDE cables (with blue connector covers) are bottom right, going past the end of the motherboard tray, to the space beside the 3.5" drive cage. You can see the CDRW drive's power at the middle right of the image.
http://i5.photobucket.com/albums/y15...ide_Centre.jpg

2) Inside rear view
http://i5.photobucket.com/albums/y15...nside_Rear.jpg

3) Inside front view
http://i5.photobucket.com/albums/y15...side_Front.jpg

4) Wiring, behind the motherboard tray. I'd love to tidy these somehow and arrange them so that there's no pressure against the side panel. See the bundle in the lower left corner?
http://i5.photobucket.com/albums/y15...loo_wiring.jpg

I also wired up the 2 fans so that the yellow RPM lines are connected to motherboard headers and their power comes from a dedicated PSU wire

[Flarkit]

TEMPS:

(Idle)
Motherboard: 24 °C (75 °F)
CPU: 37 °C (99 °F)
HDD: 23 °C (73 °F)

Cooling Fans:
CPU: 2909 RPM
Chassis (92mm): 1722 RPM
Power Supply( 120mm): 1815 RPM

(Load, running SuperPi for 20min)
Motherboard: 26 °C (75 °F)
CPU: 43 °C (99 °F)
HDD: 24 °C (73 °F)

This might not have been long enough for the case temps to be affected.

Cooling Fans:
CPU: 2960 RPM
Chassis (92mm): 1722 RPM
Power Supply( 120mm): 1815 RPM

[cadaveca]

i would take the 20 pin connector, and route it behind the psu and to the back of the case and down, if airflow was a major concern. i'd much rather block the air going out than the air coming in.

[Flarkit]

Originally Posted by cadaveca

i would take the 20 pin connector, and route it behind the psu and to the back of the case and down, if airflow was a major concern. i'd much rather block the air going out than the air coming in.

I tried it that way and found that the wire bundle would stand upright, blocking the rear fan and (partially) the path through the CPU heatsink. As it stands currently, I've tied a portion to the motherboard tray, which keeps the bundle flatter, but unfortunately covers the RAM somewhat.

I'll see if it's possible to route it along the bottom of the rear fan's housing.

Methinks a smoke test might be in order, using some incense!

[Chaz]

Are wires really going to block airflow that much? Obviously its a good idea to have a clean passage for the air, which means tucking away things like IDE cables, but will simple PSU cables make any difference to case/CPU temps?

[cadaveca]

Originally Posted by Flarkit

Methinks a smoke test might be in order, using some incense!

if you can follow the smoke trail with incense...you are not moving enough air, IMHO!

[cloasters]

Your interior temps are very nice indeed. How this was achieved without any intake(I may be wrong about that) fan puzzles me.
If there is an intake fan, I suggest covering the places where air gets into the case with high grade(expensive) masking tape. One doesn't want bits of masking tape flying about inside a PC case, expensive masking tape will stay in place for years.

With no intake fan(s), the holes are letting air into your case, so don't cover them.
Regarding the scraped insulation of one of the power wires, wrap it with three layers of electrical tape ASAP. Sure, it's only 5 or 12 volts. The amperage available in these thin wires is gigantic, unauthorised welding is not good.

[Flarkit]

Originally Posted by cloasters

Your interior temps are very nice indeed. How this was achieved without any intake(I may be wrong about that) fan puzzles me.

...

With no intake fan(s), the holes are letting air into your case, so don't cover them.
Regarding the scraped insulation of one of the power wires, wrap it with three layers of electrical tape ASAP. Sure, it's only 5 or 12 volts. The amperage available in these thin wires is gigantic, unauthorised welding is not good.

Thanks. I attribute the temps mainly to our current winter. External/room temps are around 18-23 degC.

I want to cover the holes, since those will let dust through. I will take your advice and cover the damaged PSU wire.

[Flarkit]

Hi

Just an update on this little story. Thanks to winter temps, I've been able to unplug the 120mm fan and have only a 92mm rear fan pulling air out, along with the PSU fan.

My PC is reasonably quieter than the previous incarnation and just seems to have a PSU "coil whine" currently raising the sound level above my hoped-for "soft hum".

"Cool & quiet" has become a pleasant hobby!