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Air cooling @high ambient temps

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April 6, 2012 9:48:28 AM

Hello, I'm purshasing my new rig by the end of next week. It's an i5 2500k build which I want to overclock @4.2-4.5GHz
Where I live, max temps are around 35-42ºC in summer, so I'm a bit worried about my new rig's cooling if I achieve that overclock.
My case choice is the Antec 300, which comes with 2 fans (120mm rear, 140mm top) with adjustable speed (Low, Medium, High). As far as I know, these are those fans specs:

Antec 300 140mm fan
rpm 700 / 19.8 dBA / 47 CFM
rpm 1100 / 21.4 dBA / 66.8 CFM
rpm 1500 / 31.8 dBA / 94.1 CFM

Antec 300 120mm fans
RPM 1200 / 25db / 36cfm
RPM 1600 / 28db / 56cfm
RPM 2000 / 30db / 79cfm

CPU cooler: CM Hyper 212 evo

So, now I'm trying to decide which fans to get for the 2 front fan slots that the Antec 300 has.
I'm between these 2 options (120mm):

Scythe S-FLEX - rpm 1200 / 20.1 dba / 49 CFM
Scythe S-FLEX - rpm 1600 / 28 dba / 63.7 CFM

1) I've read some good reviews about the 800-1200rpm ones, but would they be enough considering summer temps here?
2) Is 28dba too noisy?

Thanks!
April 7, 2012 12:35:13 PM

First I think you should know what mobo you want so you know what type of headers will be available. And on that mobo, will you be able to control the fanspeed through a program?

You can skip that all together if you get a fan controller. In that case, make sure the fans you will control are 3 pin. I prefer software controlled as rpms can be automatically adjust for different temps.

If you get a fan controller OR your mobo can control the voltage on the 3 pin headers via software, get the 1600rpm fans. During idling, you can lower the fan down to ~800 rpm which will be quiet.

If you have available 4 pin header on mobo for those fans, try to get PWM versions with high rpm variability.

Is it possible to get a nicer CPU cooler? If not, try to upgrade the stock fan OR add another fan in back for pull.

28dB isn't that loud, but I wouldn't like it that loud all the time. If you are running on 100% load, that is a very good noise level, but not at idle.

I have my 2500k OC @4.5ghz and my highest temp is 60C, but I'm using a Noctua NH-D14 with 2x Scythe Slipstreams @1500rpm. You should be be getting ~70C if your area is that hot. Just try to keep those temps below 75C.
April 8, 2012 11:10:35 PM

mobo: ASRock Z68 extreme3 gen3
I read it supports some kind of fan control but I don't know how customizable it is or how many fans can I connect to that mobo.

I could get an ASUS P8P67 B3 for $7 more, which has:
1 x CPU Fan connector(s) (4 -pin)
2 x Chassis Fan connector(s) (1 x 4 -pin, 1 x 3 -pin)
1 x Power Fan connector(s) (3 -pin)

Does it worth the extra money considering that P67 is older than Z68?

Thanks for your reply.

Edit: Sythe S-Flex fans have 3-pin connectors
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a c 121 K Overclocking
April 9, 2012 12:17:18 AM

If you can, just get the Antec 300 illusion model:
It will come with two 120mm 3 speed intake fans.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

I think I would test out your system with the default fans first.
It is easy enough to add front fans later if you need them.

The stock exhaust fans are sufficient to get rid of hot air from the cpu cooler.
The evo is very good, and even with higher than normal ambient temperatures, you should not have a problem.
You might get to 75c with a stress test, but that will not happen in normal operation.

As to which fans would be best, It probably does not matter much if you are not much concerned with noise. Faster fans push more air, but at the cost of noise.
If noise is an issue, and budget is not, then Noctua makes some of the best along with Scythe.
If budget is an issue, look at some $7 yate loon's.

An equally important factor is the design of the graphics card cooler.
Some cooler designs do a good job of getting heat off of the gpu chip, and show nice low temperatures in an open testbed. But in a case, they disperse the hot air inside the case, heating up BOTH the cpu AND gpu. Not good.

I think the reference direct exhaust type coolers are better in a case because they get the gpu air directly out the back quicker.

And... Now that Z77 based motherboards are available, and not too expensive, I would look at them instead of Z68.
a c 150 K Overclocking
April 9, 2012 6:07:58 AM

Asrock board is better..
April 9, 2012 8:41:20 AM

I can't find any store in my country that sells the Antec 300 Illusion, so I have to purchase the standard Antec 300 and 2 extra fans.

Is it possible to control fan speed with the ASRock Z68 extreme3 gen3 mobo?

In that case I will get the 1600rpm fans, and otherwise I will get the 1200rpm ones.

Thank you for the replies.
a c 121 K Overclocking
April 9, 2012 2:04:47 PM

mivic said:
I can't find any store in my country that sells the Antec 300 Illusion, so I have to purchase the standard Antec 300 and 2 extra fans.

Is it possible to control fan speed with the ASRock Z68 extreme3 gen3 mobo?

In that case I will get the 1600rpm fans, and otherwise I will get the 1200rpm ones.

Thank you for the replies.


If your fan has a 3 pin connector(not a 4 pin molex), then it has speed sensing and can be controlled by a motherboard with a 3 pin fan header.
Most motherboards do not have sufficient headers for many case fans.

Regardless, there are other ways to control fan speeds. A discrete fan controller, mounted in a 5.25 or 3.5" front panel is one way.
A easy way is to use a zalman fanmate which costs only about $5.

A simple wire adapter can change the fan to a lower voltage. A couple will be provided with Noctua fans.

Personally, I like a steady drone of constant speed fans. Constantly changing speeds annoy me. I just set them to a good balance of cooling vs. noise, and leave it there.
If parts get a bit hot, so be it. No damage will be done.
a c 150 K Overclocking
April 9, 2012 3:34:12 PM

Don't know, I can change my cpu fan speed (hyper 212 evo) with the asrock extreme tuner, on my asrock z68 extreme 4 gen 3. I can't change any of my other case fans (cm 690 ii advanced) but they aren't that loud so it doesn't matter.
April 9, 2012 4:30:39 PM

amuffin said:
Don't know, I can change my cpu fan speed (hyper 212 evo) with the asrock extreme tuner, on my asrock z68 extreme 4 gen 3. I can't change any of my other case fans (cm 690 ii advanced) but they aren't that loud so it doesn't matter.


Ok, I'm getting 2 S-Flex 1200rpm then. It would be ~98 intake CFM, I hope it is enough.

Thanks.
a c 324 K Overclocking
April 9, 2012 6:04:34 PM

Just FYI, you won't be able to cool below ambient room temp- so your idle can never be cooler than what temp your room is. It's impossible to cool below ambient with air cooling and normal water or liquid cooling.
April 9, 2012 7:00:40 PM

rubix_1011 said:
Just FYI, you won't be able to cool below ambient room temp- so your idle can never be cooler than what temp your room is. It's impossible to cool below ambient with air cooling and normal water or liquid cooling.

I'm aware of that.
What I want to do is trying to achieve the best stable OC possible without setting the CPU on fire when summer comes ;) 
!