View Full Version : Need help with chassis fan selection

08-01-09, 09:10 AM
I'm building my first system and I've purchased an ASUS P6T MOBO with Core i7 CPU. The case has arrived and due to an oversight I did not order any chassis fans. My existing system (also ASUS) is very noisy and I'm doing everything possible to control and minimize the sound level of this new system and I need some advice on the chassis fan(s).

Does the P6T support Pulse Width Modulated (PMW) chassis fans or not? I throught I read somwhere that it does but I can't find that info anymore. If anyone knows, please let me know.

If you're trying to minimize the chassis fan noise is there a particular brand or model that provides enough cooling for the system while at the same time mimimizing noise? If so, can anyone provide any insight on what I sould buy? The chassis case has front and rear 120mm x 120mm x 25mm fan slots.

Should I put two chassis fans in or just 1 for now and see how it goes?

Any info will be greatly appreciated.

bob saget
08-01-09, 09:52 AM
It all depends how much noise you are willing to live with i think. In my opinion, moving air is much more important than sound.
Why is PWN so important? you could also use a fan controller like these http://www.frozencpu.com/cat/l3/g47/c17/s239/list/p1/Fan_Accessories-Fan_Controllers-Rheobus_Controllers-Page1.html
I got 6 fans (counting the cpu cooler), and my system is not silent, i am not going to say its silent, but there is just a quiet hum.
For noise dampening you could also buy materials and glue them to the inside of the case. This however may raise temperatures.

08-01-09, 07:05 PM
It all depends how much noise you are willing to live with....

OK....I think I have it now. Here's the plan as I see it. www.silentpcreview.com recommends the Scythe S-Flex brand/model of case fans (among others). I read the reviews and these Scythe fans appear to be very good. As I understand it, if I'm doing this correctly I need to put in a SFF21D (800 RPM) model in the front of the case and a SFF21E (1200 RPM) fan in the rear. I could step up to the SFF21F (1600 RPM in the back and put the SF21E in the fron but it's been suggested on another forum site that this is overkill and may increase the noise. I'm a bit fuzzy on why the front fan needs less powerful than the back fan. Can anyone explain this or am I all wrong and that I need two fans of the same speed in both the front and back?

Also in regard to the CPU fan..... It's highly unlikely that I'll be overclocking the system so I'm wondering if putting two 120mm fans in the case in conjunction with the stock cpu cooler in conjunction with the case that has the chimney and vents for the graphic card plus the Enermax Ps Emd525Awt Modu82+ 525W 17Db Atx12V quiet PSU and the Sapphire Vapor-X 100273L Radeon HD 4850 1GB 256-bit GDDR3 which are both supposed to be very quiet and very cool, whether I really need to take that extra step and add a after market CPU cooler?

08-02-09, 03:42 AM

I have 7 Scythe 120x25mm fans in my latest water cooled case and 5 120x38mm in my latest air cooled build. They seem to work and tend to be cheaper than the competition.

WRT using the louder fan in the rear of the case, I am not familiar w/ the article but would guess that, being farther away from you and blocked by the case, you can afford to go w/ something louder without increasing the overall noise too much.

I have filters on all of my inputs and therefore always run w/ positive pressure such that I know that the air into the case is always coming through the filters. I also run all of my cases w/ dynamic temperature based fan controllers, either of my own design or using fans w/ built in thermal probes. Scythe has a new fan controller which appears to have these capabilities but I can't vouce for it, although I have used their manual controllers just to view temps and rpms. My fans run at ~7v under low load situations and then ramp up as the cpu/gpu temps go up. Also, many/most of the Asus MBs support dynamic control of the case fans via a 3-wire (not pwm) connection so this may eliminate the need to buy a seperate controller. WRT the cpu, it should similary vary per temp and if you go for an aftermarket cooler, as I'm sure you will eventually, go w/ PWM for the cpu.

You say you want to OC but then you talk about wanting silence and of using an 800rpm fan. Engineering is all about making trade-offs. You'll have to decide which is really more important to you.

Other things to consider. The 140mm fans tend to have better flow vs noise so, if you case can accomitate them, they are good if silence is your goal. Scythe has some 140mm fans and so does late loon (very inexpensive). Scythe has some 140mm fans which use 120mm mounting holes and, for other fans, if they don't come w/ a 140->120 adapter, you can buy them.

I am using 38mm thick fans in my current build because they can generate more pressure. I am a big believer in controlling the flow of air in the case such that it is forced to go through/over the the parts that need to be cooled. It does little good to have most of the air come into your case and go right out the back without touching anything. Anyway, such restrictions, plus the input filters, create the need for the greater pressure capabilites you have w/ the 38mm thick fans. You just need to be sure that your case has room and using a 38mm fan on the rear of the case, above the cpu area, can limit which aftermarket heatsinks you can use.

Good Luck!

08-02-09, 10:34 PM
Go with a Panaflo, they have about 70cfm at 30dba and have better bearing they will last longer, never go with the cheap ones they will be louder because of the Pulse Width Modulated (PMW) always go with a good fan. I am using two of the Panaflo to cool the radiador and a couple of highend led fans and can bearly hear them, good insulation inside the case will make things quiet and look cool to.