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Case Fans

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July 10, 2006 4:15:49 PM

Ok,so i have an NZXT Lexa, all stock case fans. i added a 70mm at the bottom of the case, its kind of irrelevant to cooling, but o well..



to the questions.

as most of you know the Zalman 7000-Cu blows air down on the CPU. My rear 120 is set to exaust and sidepanel 120 is set to intake. I think this is in effective because the zalman blows air down.

Would making the rear intake and side panel exaust lower the temps?

The rear would directly feed the zalman air and the side would exaust air out of the PC. this makes sense to me. Your thoughts please.


Thanks

More about : case fans

July 10, 2006 6:59:48 PM

BuMp!
July 10, 2006 8:04:33 PM

Actually I don't think so.

Your cpu fan blows air down and if your side is an intake it blows air from the outside, which is cooler, directly over your cpu fan which takes it and blows it down through the cpu heatsink and out. It will blow out in all directions but your capacitors to the left of the cpu heat up quit a bit so the air blows across them then gets exhausted out the back.

If you reversed the side and rear fans the side fan and the cpu fan are pulling air in opposite directions, the side fan would essentially be exausting air that just came into the case from the back, you want to exhaust hot air not cool air.
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July 10, 2006 8:35:27 PM

try it and see?
July 10, 2006 8:39:24 PM

Someone posted a site around here recently that did tests with many different fan configurations. I don't have a link handy but I'll post it if I find it. What did they find? The best airflow was with fans on the back blowing out. Period. Nothing else. There was also benefit with fans on the top of the case blowing out if that was available, but every other configuration (fans on front blowing it, etc, etc) showed higher internal temps.
July 10, 2006 8:43:42 PM

i think you mis under stood me.





the sidepanel fan isnt lined up with the CPU, its suppsoed to cool the GPU.

so do u think i should reverse them now?
July 10, 2006 9:14:21 PM

I'm still not too sure...

If you make it an exhaust it will remove the hot air from the GPU area so that it doesn't sit there but then again it's not getting cool air either. I think that with the 70mm intake at the bottom you could turn the side into an exhaust but I'd still have the rear as an exhaust.


Basically I'd make both exhaust.


Maybe you could add another 120mm over the 120mm you have right now in the side? Then you'd have 2 - 120mm and a 70mm intake and 2 - 120mm and 1 -80mm (i'm assuming that's what the top blow hole is) exhaust.
July 10, 2006 9:34:38 PM

Quote:
i think you mis under stood me.





the sidepanel fan isnt lined up with the CPU, its suppsoed to cool the GPU.

so do u think i should reverse them now?


I'll give my fan setup for an example. I have one 80 mm fan blowing in from the front, along with an unused opening. I have a 120 mm fan on the side, similar to yours, blowing out, two 80 mm fans at the back blowing out, and a 80 mm blowing out the top. Five fans total moving air. There is probably a bit of negative pressure in the case from all the fans blowing out, but heat doesn't get a chance to stick around. The temps stay in the high 30's to 42c max, and this is in the desert where the ambient air temp is warm to lsay the least.

So yes, as to your original question, I think that making the side and rear fans blow out (exhaust) would help lower the internal temps.
July 10, 2006 9:51:19 PM

The side should intake unless you want your graphics cards to get hotter and the back should exaust becasue it will drag heat off the side of your heat sink and also from the far side of your case over the heatsink.
July 10, 2006 10:00:15 PM

Quote:
The side should intake unless you want your graphics cards to get hotter and the back should exaust becasue it will drag heat off the side of your heat sink and also from the far side of your case over the heatsink.


the issue is my gfx card is below the 120mm fan. the sidepanel fan does nothing bit pull air in and blows it over the PCB
July 10, 2006 10:28:44 PM

Yeah I think you should mod that side panel with another 120mm align to the HSF to blow cool air directly to it. Use a dremel to do the cutting and it is not that difficult to do so. I've this kind of mod before and I got some good results in cooling.
July 10, 2006 10:48:11 PM

My graphics card is watercooled and the water cooler has its own fan. I did as suggested, turning the side fan from exhaust to intake, but haven't noticed any temp difference at this time, but I haven't loaded it under a game yet. Can't say whether what I had was the best or not, only how it works on my particular setup.
July 11, 2006 12:26:46 AM

Quote:
Yeah I think you should mod that side panel with another 120mm align to the HSF to blow cool air directly to it. Use a dremel to do the cutting and it is not that difficult to do so. I've this kind of mod before and I got some good results in cooling.


yeah....im not gonna mod it. not a fan of cutting into my case..yet.

anyways, ill try it and report back, ill prolly do it over the weekend when i have time to play with the fan and figure something out.
July 11, 2006 1:08:19 AM

I doubt it will make a massive 20 dg diff either way.....

There are only a couple of variables so just try and see....

I usually like to think my case has negative pressure and onie way flow but I sometimes doubt that this is the most effective way to cool a case.
July 11, 2006 2:28:57 AM

right now im thinking this.


Rear intake.

side exaust.

bottom exaust

front intake

and finally top intake. the case sits on a desk the air above the case is cool.
July 11, 2006 11:22:19 AM

That seems completely counter intuitive.
July 11, 2006 2:07:15 PM

Yeah, I really don't see that working out too well. Case fans are set up like they are for a reason. If there was a better way to configure the intake/exhaust setup for better cooling, you gotta think some of the case manufacturers would have caught on to it.
July 11, 2006 2:41:51 PM

Quote:
right now im thinking this.


Rear intake.

side exaust.

bottom exaust

front intake

and finally top intake. the case sits on a desk the air above the case is cool.


Since warm air rises, it seems like your warm air would go out of the bottom and side, and then up the case to rear intake or top intake. There is a good chance you would be sucking in the already warm air.

Here is a random question... does anyone ever put a fan inside of the case (i.e. not intaking or exhausting) for the sole purpose of swirling air around inside of the case? It seems like that could help those warm air pockets since the air would be moving all around.
July 11, 2006 2:51:37 PM

The closest I've seen to that is people mounting fans using brackets attached to PCI slots, and aiming them at whatever they want (usually a gpu).
July 11, 2006 3:06:26 PM

Sounds hokey to me but you never know what will work. Unless someone has access to what mechanical engineers use for determining aerodynamics around objects all you can do is try.

What I do know is that hot air rises and cool air falls so drawing air in from the top and expelling it out the bottom doesn't make much sense. Plus I think you'll create a turbulant area right at the top where the heat will rise to but will have no where to go out.
July 11, 2006 3:20:35 PM

Quote:
i think you mis under stood me.





the sidepanel fan isnt lined up with the CPU, its suppsoed to cool the GPU.

so do u think i should reverse them now?


have the front, bottom, and side fan as intake and the rear and top fans exhausting...general rule of thumb, front and side in and top and rear out...some cable ties might help with the airflow as well...
July 11, 2006 4:39:18 PM

That's a very different way to do it, but for a short experiment, why not? You may discover what other's have missed. The only thing that I can see which might be odviously backwards is the top fan. Try it the way you wrote, measure temps, and then turn the top fan to exhaust and measure temps again. Then report back the results. Whether it works or not, the results will be interesting for everyone, even if we only see what doesn't work.
July 11, 2006 7:59:24 PM

Quote:
Yeah, I really don't see that working out too well. Case fans are set up like they are for a reason. If there was a better way to configure the intake/exhaust setup for better cooling, you gotta think some of the case manufacturers would have caught on to it.



manufacturers set it up wor work with stock heatsinks. Stock AMD and intel heatsinks pull air off the CPU and the rear exausts the warm air out.

thats why i wanted to flip the rear fan. my zalman pushes air down so there is a negative reaction between the CPU fan and the rear exaust.
July 11, 2006 8:05:48 PM

Quote:

manufacturers set it up wor work with stock heatsinks. Stock AMD and intel heatsinks pull air off the CPU and the rear exausts the warm air out.

thats why i wanted to flip the rear fan. my zalman pushes air down so there is a negative reaction between the CPU fan and the rear exaust.


I've never seen any HS/fan to doesn't blow air down onto the HS, stock or not.
July 11, 2006 8:06:07 PM

The only way to find out is to go for it. Give us a report back when you're done. This is kind of interesting.

Quote:
I've never seen any HS/fan to doesn't blow air down onto the HS, stock or not.


That's what I was thinking, but I wasn't completely sure.
July 11, 2006 8:36:56 PM

Quote:

manufacturers set it up wor work with stock heatsinks. Stock AMD and intel heatsinks pull air off the CPU and the rear exausts the warm air out.

thats why i wanted to flip the rear fan. my zalman pushes air down so there is a negative reaction between the CPU fan and the rear exaust.


I've never seen any HS/fan to doesn't blow air down onto the HS, stock or not.

both my Pentium 4 socket 478's pull air off. i never used the stock AMD and i speculated it did too. But ill try flipping the fans and find out.
July 11, 2006 8:38:53 PM

My stock pulled air down into the heatsink.
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