How much CFM do you need at the front fan?

Happy Hopping · Post by **Happy Hopping** » Sun Aug 10, 2008 9:47 pm

If my rear fan that comes with the system by the manufacturer (HP) is a:

NMB-MAT PWM fan
129.957 CFM ,
3600 rpm,
12V,
50 dB fan.

I also have 4 hard drives (2 x Ultra SCSI, 2 SATA) at the front but NOT directly at the front cooling fan spot, but just above the 12 cm fan spot. See photo where the green cables are at the front

The sys. only get up to 129.957CFM when I play computer games. All other time for business use, it's quite quiet and obviously isn't drawing too much CFM

How much CFM do I need at the front bottom fan?

nick705 · Post by **nick705** » Mon Aug 11, 2008 2:36 am

The question of how much CFM you "need," whether at the front or the rear, is a bit meaningless without knowing your component temperatures.

The fans are there to keep your temps within acceptable limits, not to generate airflow for its own sake.

dhanson865 · Post by **dhanson865** » Mon Aug 11, 2008 9:40 am

I use just enough fan in the front to keep my hard drives below 35c at idle and below 40c at load.

It doesn't take much.

Check out speedfan from http://www.almico.com/speedfan.php or HDTune 2.55 (the free version) from http://www.hdtune.com/hdtune_255.exe for a way to monitor your hard drive temps.

Post by **NeilBlanchard** » Mon Aug 11, 2008 3:47 pm

Hiya,

129.957 CFM?!

That's enough to float a small hover craft! THREE decimal places -- I smell marketing bullpuckey.

Cistron · Post by **Cistron** » Mon Aug 11, 2008 3:58 pm

NeilBlanchard wrote:Hiya,

129.957 CFM?! That's enough to float a small hover craft! THREE decimal places -- I smell marketing bullpuckey.

European notation - he's building a windtunnel!

Happy Hopping · Post by **Happy Hopping** » Tue Aug 12, 2008 12:31 am

NeilBlanchard wrote:Hiya,

129.957 CFM?! That's enough to float a small hover craft! THREE decimal places -- I smell marketing bullpuckey.

I am the one who actually do the calculation. They list the CFM is cubic m as 3.68, so we I divide by the Cube of 0.3048, the no. is 129.957 CFM

Happy Hopping · Post by **Happy Hopping** » Tue Aug 12, 2008 12:33 am

nick705 wrote:The question of how much CFM you "need," whether at the front or the rear, is a bit meaningless without knowing your component temperatures.

The fans are there to keep your temps within acceptable limits, not to generate airflow for its own sake.

I called HP, neither the bios nor any HP software do temperature monitoring.

I would like a software to do CPU or whatever other temperature it can monitor prior to a PC Game

then take the same reading again just after the game.

Obviously the GPU is monitor by the Nvidia software

tuz · Post by **tuz** » Tue Aug 12, 2008 5:36 am

Hello,

give HWMonitor a shot, it seems to be compatible with most hardware out nowadays and reports temps for CPU, GPU and mobo sensors along with your hard drive (if it has support for S.M.A.R.T.) - a great all round app. Oh and it'll report voltages and fan speeds if you're interested in those.