Neg. or Pos. case preasure?

[xraymongral]

OK, I am getting a Addtronics 6896 case, and I am scratching my head here wondering if I need to a higher air volume flowing in or flowing out of the case? It seems that I have heard of people doing it both ways, so which is the better way to do it?

Thanks

 

[toph99]

equal pressure i'd say

 

[jsbush]

More exhust is better.

 

[Mikewarrior2]

Equal is ideal, but my case is slighly positive(slighly more in)

my case is here .



Mike

 

[shiznut123]

mine is negative
i have 60cfm out and 30 in

 

[sweetca]

this is a completely new concept for me. i just leave my case off and have a big ole house fan blowing on everything! =)

 

[Viperoni]

sweet, then you'd have total positive pressure.
I'd prefer positive over the negative.

 

[Amaretto747]

just read an article about that, negative case pressure is better.

 

[Usul]

Technically speaking more pressure = better thermal transfer.
Right, Mike?
And, pratically speaking, negative brings in lots of dust from every stupid little hole.
On th other hand, positive may launch your CDs like bullets when you take them out

 

[Mikewarrior2]

Me personally, I like a bit of positive in order to keep some dust out(in order to do this, you have to filter your intakes).

Technically, more pressure means more "fresh" air coming into the case. If you don't have enough exhaust, this can easily backfire, though.

I think its the same way with too much negative presure... not enough "fresh" air coming into the case.

So I think a median is good... I hae about 120CFM in, 110CFM out... more than the average user needs, but even enough for my needs.


Mike

 

[dadx2mj]

I feel that having equal intake and exhaust is best. Next best is negative presure because you need to get the hot air out of the case. When you have positive presure it is real easy to get hot spots and generaly disrupt air flow. Negitive presure may cause the case to get more dust build up but I have never seen a case that did not need cleaning every month or so anyway

 

[Hanky]

Mike,

>>I have about 120CFM in, 110CFM out...<<

Does that include your PSU (exhaust) fans?

 

[jsbush]

Humm... So should I put my two Antec fans in front of my SX830 and put my 80mm exhust?

 

[sweetca]

i found that when you have a really hot system because of overclocking and fast video cards (v5 or GTS) to just leave the case off. i have a rather large case (6 visible 5.25, 6 hidden 3.5, 2 visible 3.5) and when it was all closed up, you could have fried an egg on the outside of the case. to fix this problem, i just took the case off and attached a 3 foot house fan to the side of the tower and heat problems are a thing of the past. i dont think that would be either positive or negative pressure, there is nothing surrounding it to differeniate between the two.

i have also never had to clean my case...ever. i am not sure why this works so well...everything ive ever read said never have the case off. but, this works like 100% better, for me anyways. it looks like a big PITA but its really not. oh well, just my 2 cents for the day =)

 

[dadx2mj]

Jsbush I have the SX830 I got two more 80mm and filled up all the fan spots two front intake two back exhaust my case temp is the same as ambeint room temp can't get much better than that

 

[jsbush]

I'll add another fan and see.

Should I put the strongest fans in the back or in the front?

 

[toph99]

if you have positive pressure. you are having more air to transfer heat away form components, but then it stays there and the case temp will go up because the hot air isn't being expelled fast enough. with a negative pressure, not only do you get dust on everything, but there isn't as much air flow over your components(like on the cpu's hsf, there isn't as much air for the fan to blow over the heatsink to transfer the heat) and you end up with hot components. thats why i think that equal is best, but whatever works for you

 

[KouklatheCat]

My case pressure is almost equal. 85 cfm in and 88 cfm out. I listened to Mikewarrior, he helped me set it up and my CPU dropped 8 degrees. Temps measured with ASUS probe (in accurate I know) and at load.

 

[Hanky]

KouklatheCat,

according to your System Rig page you calculated your values (85in,88out) without considering the PSU fans which are usually exhaust fans, so your case pressure seems to be more negative than you think.
I believe one has to consider the PSU fans in the calculations, but I'd like to hear Mikewarrior's word on this...

 

[KouklatheCat]

Id be interested to hear what Mike has to say also.

 

[Mikewarrior2]

Hanky, And others,

Yeah, that includes my power supply fan. While some power supplies have a hard time expelling air from teh case, enermax's assist the rear &quot;exhaust&quot; fan. So currently, I have the enermax + 2 90mm L1A panaflos' exhausting air from my case.


Mike

 

[Hanky]

Mike,

Do you have the Enermax 330 W PSU?
If so, do you know how much air it moves out of the case?

 

[jsbush]

ARGH!!!! Just put another fan in my computer, to noisey. Should I get 4 Papst 8412NGL fans like Hanky sujested in the other topic? They move 20CFM. That would make 40 going in and 40 going out, is that enough?

 

[Mikewarrior2]

Low 20s is what enermax told me, but since its &quot;throttled&quot; i'm not sure how much currently... case is pretty cool right now.


Mike

 

[Hanky]

Mike,

I'm almost sure it's more than 30cfm, because I have a Papst 8412NGML (27cfm) as an exhaust fan right next to the PSU and it feels as if the Enermax' fans move a lot more air!

jsbush,

as GizZo said in the other topic the NGML model would be a better choice because the noise difference between the NGL and the NGML is very small (but I can hear a difference between the NGL model as my front intake fan or the NGML...). GizZo also said Papst fans are tough to find in the &quot;New World&quot;. Didn't know about that...