Fans - stronger at the rear or front of case?

Alexrose1uk

Alexrose1uk

Alexrose1uk

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I've just got an older antec server case, now unbeknownst to me it doesn't take 12cm fans, only 8cm fans, so I'm limited in what I can fit (have a lovely Scythe 1900RPM slipstream here too :(). As it was used its got some 8cm Akasa and YS tech fans with it.

Now, for best airflow and cooling, do I put the stronger fans in the front of the case behind the drive caddys, or do I fit them at the rear of the case behind the CPU cooler.
The fans I have are 2x Akasa 20CFM, 1x Akasa 30CFM, 1x YSTech 45CFM.

Might sound like a stupid question but I thought someone might know, hell it might not make any difference, but I can't see it covered in any of the cooling stickys. Once I've got it sussed I can go compare to my current case and see which one gives me the best temps, and which case is going to my brother!
 
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in my old case (thermaltake eclipse DV) i had a normal 120mm thermaltake fan at the front and a normal 92mm thermaltake fan on the side as intake, my outtake was a 120mm delta (the one they sell on OCUK) this actually caused my temps to raise, but i was not aware of it until i replaced the side fan with a vantec tornado, which knocked a good few degrees off my temps.

summary, make sure intake and outtake match in terms of airflow.

also is there room to mount 120mm fans if a drill was used?
 
Would only be a side fan if I was to do so, unfortunately the rear of the case is recessed awkwardly for 2x 80cm fans so for the moment, until next month when I could think of perhaps changing to say an Antec 300, Im stuck with what I've got. The current case is running 22cm fan on the side, a 12 on the rear and none in the front.

Due to higher CFM, its probably slightly better like that for cooling, but unfortunately its slightly thinner inside, so I can't fit a better cooler on to drop temps than the Zalman I have at the moment, and ideally dropping CPU temps are my main aims.
Originally I'd hoped this case would accept 12cm fans front and back, so had planned to move my 12cm akasa to the front, fit my slipstream to the rear, and change the CPU cooler to one of the new Core Contact coolers next month, as they seem to be beating the TRUE and Tuniq in the reviews, and are cheaper too.

From what you're saying, I'd guess with what I have it'd be best to go for the Y.S in the rear along with one of the weaker Akasa fans, and the stronger and other weaker AKASA fan in the front.
 
i never tested it properly, but i would say make sure there is no buildup of air pressure nor is there a vacuum in the case. fans dont need to be at the same CFM or RPM
 
okay at the moment i have 2 x Scythe 1900RPM slipstream.... one front(1900RPM) and one Rear(1700RPM) that sound okay to you? or could i try soming to make airflow better?
 
I personally would have more air being sucked in through a filter then drawn out, positive pressure if you like within he case, the reason for this is that if you do it the other way the case will suck air and therefore dust through any opening in the case causing a dust fest.
 
i have an antec nine hundred and i have a very very positive airflow (4 intakes and 2 outakes) and many fans in the middle (i think theres bout 17 all togther)
I get very low temps but it is very noisy!!!
 
Well in my antec 900 I have 2 800rpm at the front and a 1200rpm on the rear , cos I thought with the fan being at the back the noise wont be as noticable, so thats why Ive got a faster 1 on the back. EDIT: Plus I have the big mother of the fan sucking the air out of the top of the case, but thats set on the lowest setting, whatever that is in PRM?
 
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It's contentious, as you can see from the preceeding 5 posts.

I will stick with more coming in than going out. If you take more out then your volume of air inside the case will be lower due to the lower pressure. Less volume = less atoms to take the energy away from the components.

With intake>output the pressure will force the air out of any gaps (eg between drive bays and ventilation holes) keeping dust down.

We could get into p=v/t and explain why if the volume is higher, the pressure will be correspondinly higher and won't make much difference to the temperature, but this isn't a physics lecture.

What I will say is that it can be dependant on case. The actual airflow is more important than the ratio of in:out. Your case might work well with a faster airflow from the input, or it may respond well to air being dragged out.

Or to summarise a completely different point: try combinations.

Eg try 35+40 at the front and the two 20s at the rear (eg input 35>output), then reverse it (output 35>input). Then try a slight differential of each (20+35:20+40). eg input 5> output and output 5> input

There's only 4 possible combinations of those fan combinations (assuming the two akasa 20s are pretty much identical), so try them out and see if any are markedly better.
 
Positive Airflow here! (i.e more air being blown in than extracted) :cool:

Temps are good and I noticed the case interior is less dusty as all intake fans have dust filters . . . and due to positive pressure from the intakes air is not being sucked in through cracks, vents and drive bays! :D

As with most things . . . it's a matter of personal experimentation to see what works best for you! :)
 
+1 for in>out. Just seems to work better from my experience with the cases I've had. Try out different combinations to see which works best for you, but as a rule of thumb I use front/bottom = in, rear/top = out.
 
In my akasa eclipse case ive got 5 sharkoon silent eagle 2000 rpm fans (2 on a TRUE black) 2 front intakes, 1 of which is in a kama bay and 1 exhaust. The case is very cold and i have very little dust building up in it,
 
i would have a stronger fan at the front and not so powerful fan at the back.

i have 25cm intake fan in the front on full speed, 35cm intake fan on the side on full speed, 12cm outtake fan on the back on half speed (1000rpm), 17cm outtake fan on the top on half speed
 
Well I've kind of side jumped the whole proceeding. My brothers e5*** machine is getting my old Zalman and the server case, although I'll still have a fiddle, but as he doesn't need/want his overclocked just yet as he doesn't play as many video games, mostly uses it for watching films etc it won't be quite as important to him.

I've ordered an Antec 300, 2 more 12cm scythe slipstream 1900rpm fans and a Core Contact cooler on it's way. From testing at 1900RPM, frostytech reckoned they genuinely did about 90CFM average, so 3 of those, the 2 built in exhaust fans and the new CPU cooler should kick temps into touch in comparison to my current setup. Frosty also reckoned that the Core Contact cooler is approximately 10 degrees closer to ambient than my current Zalman with a load of 150w, so with the improved case cooling Im hoping to see somewhere near that as a drop in temps :)

Cost a bit of money I didnt expect to have, but then some plans got unexpectedly cancelled so fancied putting some money into cooling my machine down. Due to the layout of my room (I have the airing cupboard in here), I have above average ambient temps so every little helps.


At the end of the day I'm happy I've provoked this conversation anyway, as it doesn't really seem to have been covered elsewhere. What I think I'll do is try and fit one of the stronger and 2 weaker fans into the front of the server case, and 2 in the back, so the airflow in is slightly higher than out :)
 
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