Case with filtered intake for positive/neutral pressure?

[Snowdog]

I hate negative pressure. My current PC was negative pressure and it pulled dust bunnies in everywhere, Any unused connected had a dust bunny. Evil.

It was a Antec sx 635. With one exhaust and the stock power supply which ran exhaust at high speed all the time. When the power supply failed and I put in a new quiet one, I quickly realized how negative the pressure was, it was causing air to stall in the power supply even though it was turning and trying to exhaust, it wasn't overcoming the exhaust fan, so I took the only exhaust fan (80mm) and put it in the only intake slot. Problem solved. I now have positive pressure and enough airflow to keep my case temp at 28c (room is 24c) and CPU at 38c at idle rising a few degrees under load. I put some AC filter over the intake so I am not sucking dust. It is a kludgy solution and that full speed 80mm is loud (as is the CPU cooler etc..) and if I ran it slower air flow wouldn't be adequate.

Anyway I want to build a new system that is quieter and not negative pressure, if not positive at least close to neutral so it doesn't pull in dust everywhere. I have a dusty environment.

I am searching for a case with filtered intake that at least balances out-take. At first I thought the Sonata might do it, but the front fan isn't really intake. Now the only thing I see is the Solo. Seems quite good.

Anything else with decent filtered intake?

[Bluefront]

If you want a really effective dust filter solution for your setup, you'll probably have to DIY. There are no good stock cases that are setup for a dusty house or office. Here are some of the dust control computers I have built recently.

[IsaacKuo]

It was a Antec sx 635. With one exhaust and the stock power supply which ran exhaust at high speed all the time. When the power supply failed and I put in a new quiet one, I quickly realized how negative the pressure was, it was causing air to stall in the power supply even though it was turning and trying to exhaust, it wasn't overcoming the exhaust fan, so I took the only exhaust fan (80mm) and put it in the only intake slot. Problem solved.

You incorrectly guessed at the problem, and as a result you came up with the wrong solution. The only reason why the PSU could be "fighting" the exhaust fan is if there was insufficient intake area or the airflow had a severe internal bottleneck. Very few cases have severe internal bottlenecks, but the vast majority of cases have insufficient intake area. Most cases have intakes that are severely restricted.

You would get better airflow and better temperatures by putting the exhaust fan back where it was originally, and increasing the intake area (the easiest method is to remove PCI slot backplanes).

That said, a typical 80mm fan running at full speed is pretty noisy and may be producing too much airflow. This is the reason why you have so much dust in your computer. My computers live in a very dusty environment with many pets. However, because my fans run at slow speeds, the total amount of airflow is reduced. As a result, it takes a long time for dust to build up. I have both negative pressure and positive pressure rigs--but since I don't use any filters on any of them, the dust buildup is the same.

For your setup, I'd recommend increasing the intake area by removing the PCI backplanes, and undervolting the exhaust fan to reduce noise and airflow. You may actually end up with about the same total airflow as you have right now, since the PSU and exhaust fans will be working in parallel (currently, they are working in serial so the airflow is limited by the 80mm intake fan).

[Snowdog]

You incorrectly guessed at the problem, and as a result you came up with the wrong solution. The only reason why the PSU could be "fighting" the exhaust fan is if there was insufficient intake area or the airflow had a severe internal bottleneck. Very few cases have severe internal bottlenecks, but the vast majority of cases have insufficient intake area. Most cases have intakes that are severely restricted.

You would get better airflow and better temperatures by putting the exhaust fan back where it was originally, and increasing the intake area (the easiest method is to remove PCI slot backplanes).

That said, a typical 80mm fan running at full speed is pretty noisy and may be producing too much airflow. This is the reason why you have so much dust in your computer. My computers live in a very dusty environment with many pets. However, because my fans run at slow speeds, the total amount of airflow is reduced. As a result, it takes a long time for dust to build up. I have both negative pressure and positive pressure rigs--but since I don't use any filters on any of them, the dust buildup is the same.

For your setup, I'd recommend increasing the intake area by removing the PCI backplanes, and undervolting the exhaust fan to reduce noise and airflow. You may actually end up with about the same total airflow as you have right now, since the PSU and exhaust fans will be working in parallel (currently, they are working in serial so the airflow is limited by the 80mm intake fan).

I agree it would give better temps/quieter by opening intakes and putting the fan (or slower one) back at exhaust. But this would be at the expense of dust.

Right now my temps are adequate and I am running filtered positive pressure; air is blowing out the empty exhaust fan grill in back. I am not going anywhere else with this system. It is old (AthlonXP, Nforce1), the CPU cooler is noisy, the HD bearings are loud etc. It only has one 80mm intake and exhaust. Not much to do with this. I am happy to cut down on dust and keep it from being sucked into every crevice/connector.

This is essentially historical. Now I am interested in Planning a new system. With at least more neutral pressure and more quiet from the get go.

A Solo case seems to one of the few that looks nearly balanced to me. With 120mm exhaust and two 92mm filtered intakes, with fan control I should be able to achieve near positive pressure with filtered intake.

Bluefront: I have seen your work. I am not up for anything that ambitious, just trying for an improvement based on standard components and if anyone has a better case recommendation than the Solo for achieving this?

[IsaacKuo]

I wouldn't worry about "balancing". If you're going to do positive pressure with a filter, then you should really just look at the intakes--more intake area is better. Since the intakes will be restricted by the filters anyway, you don't have to worry about adequate exhaust area. On the slim chance that you need more exhaust area, you can always simply remove some PCI slot backplanes.

But I REALLY wouldn't worry about insufficient exhaust area. Like I said, the great majority of cases have insufficient intake area.

For best effect, you want to only have intake fans. Ideally, the PSU should either be fanless, or the fan should be flipped so it acts as another intake fan. Flipping the fan would mean you'd need to customize your own filter on it, though. The better solution would be a fanless PSU.

Alternatively, you can use a case like the P180 series with seperate air chambers for the PSU and the rest of the case. With a P180 series case, the PSU chamber can be negative pressure, while the rest of the case is positive pressure. The P180 has slots for two air filters--one for the PSU chamber and one for the main chamber. The computer can be cooled with two fans--the PSU fan creating negative pressure in the PSU chamber, and a 120mm intake fan in the upper chamber.

[Snowdog]

By balancing I meant turning down the exhaust fan or removing it, while turning up the intake. I have no expectation of having inadequate exhaust, it is the search for adequate filtered intake that is difficult.

I find modern, quiet power supplies contribute minimally to exhaust (unless case is very hot or system is redlined while gaming) so I am not concerned about that over driving the exhaust side with the power supply.

The P180 does a lot of reorg for minimial benefit and some cable reach problems. I am not a fan of this case, though I love the looks in gun metal black (P182).

I think the ideal case would be a bigger P150/Solo, maybe with ducted isolated power supply chamber(but still where it is). Dual filtered front intake 120s. That should allow slow turning, quiet, positive filtered pressure. Oh and make it gun metal black like the p182.

Anything else that may be a better option than the Solo?

[IsaacKuo]

Remove the rear fan rather than turn it down. You want to only have intake fans.

Whether the PSU fan ramps up unacceptably depends on various factors. Most of us here on SPCR have noise reduction as a major goal. As such, we like to have as little airflow as required to keep the components cool enough--this typically means the exhaust air is rather warm. A PSU encountering such warm exhaust air will ramp up its fan.

If you aren't concerned about noise reduction, then this won't be a problem.

Also, it's a lot easier to find high quality silent 120mm fans than 92mm fans. Unfortunately, the Antec Solo uses 92mm intake fans. Again, if noise reduction isn't a priority for you, then this won't be a problem.