Making the Pundit CPU fan silent

GrahamGarside · Post by **GrahamGarside** » Mon Jan 10, 2005 6:37 pm

I've been building a pc based around a celeron d 320 and the asus pundit-r
anyone here who owns one of these will tell you they can be quite noisy, even with q-fan enabled

I've not got to work on the psu fan yet but I've had some luck getting the cpu fan to be practically silent

In the pundits bios (before the latest one as this removes qfan voltage and temp options) there are options for what voltage the fan should start on and what temp it starts at.

The lowest option is 4v, which is still audible and runs at around 2000rpm
also once it's got the temp below the startup temp it doesn't shut off,
these were the two factors I aimed at fixing

Getting the fan to run on a lower voltage can be done it one of two ways. One is a resistor on the fans 12v line to take it down to 7v, the second is to disconect the ground from the connector and connect this to a 5v line on a molex, the first one is the better option as you will keep the rpm readings
you need to keep the voltage setting in the bios at 4v so the fan will actually try and start up at less than 2v, which won't spin, only once the cpu reaches a high enough temp will the fan begin to spin, and remember the most it will ever reach now is 7v
Now what you need to do is set the temp for the fan to start up at quite high, I have mine on 55C and the full speed option at 75C, both within intel limits
what happens is the fan doesn't even start up on mine till it reaches ~60C, under load conditions it spins fast enough to keep it at this temp within a couple of degree tolerance, 62 is the most I've seen it on and it was still silent.
Now what happens when the cpu drops below this temp is the fan slows down, or at least trys to as it reaches a voltage that it just won't operate at and so stops, the cpu reaches 60 again and it starts up and it keeps the temp there and because the fan is so quiet the starting and stopping isn't noticable, my original idea of having the fan stay stopped wouldn't work because even idle and with a cpu cooling app running, passive cooling isn't enough for the prescott core even at such low mhz

I must note this is with the vent over the cpu modified with an aluminium grill vent, even with the normal case on the fan would still keep the cpu at this temp no matter how fast it would have to spin so it could still work up to audible levels with an un modified case though they would only be the same as before the mod, and at idle it may still be able to get below what it would have been before
also my cpu is underclocked and soon to be under-volted.

Doing this on my system has silenced the fan, only putting my ear within a couple of inches of it can I hear it, so now I can only hear the psu and hard drive and I think I'm going to have to swap this maxtor plus10 for a samsung

cwl999 · Post by **cwl999** » Sat Feb 26, 2005 2:56 am

I'm running a Pundit-R with a Celeron 330D with two Tv Tuners, DVD and obviously a HD. These things are lovely.

I agree that the system isn't exactly quiet so I stuck a Fanmate2 onto the CPU fan. Suprisingly, it doesn't make a great deal of difference no matter how far you turn the knob.

This isn't because it's doing nothing, it's beacause the PSU fan drowns out the CPU fan.

My temps after Prime for 30 mins are 60CPU and 48MB with the CPU fan running at 2.1K. This is with the fanmate set at it's lowest!!!!. At the mo, the PSU fan is sounding like my stock Sonata PSU (i.e. loud). Methinks I'll need to do something.

I know that the CPU fan can SCREEEAAAAAMMMM at 5K revs but it won't get there until QFAN reaches 70c. BTW I'm running the latest beta BIOS so have lost the configs in QFAN.

The PSU fan definately produces a whine, no matter what temps. Sounds like a quiet growl. Since QFan doesn't control the PSU fan, I can't really say if the whine is cause by PWM or not. I'll stick my second fanmate onto the PSU fan later and so if it can sure this problem, otherwise I'll see if I can source an 80x15 Panaflo from Dorothy.

Whist browsing the internals, I noted that the CPU fan has the following markings.

ASUS
MODEL DE07015R12U
DC 12V - 0.70A -051
Hydraulic Bearing

This thing is almost as quiet as a Panaflo L1A or YS-Tech

GrahamGarside · Post by **GrahamGarside** » Wed Mar 02, 2005 4:53 pm

the problem with the psu fan is it's starved of air. I'm preparing to cut some holes in the case, one over the cpu and another inbetween the optical drive and psu.
I've also switched the psu fan over to 5V which silences it and the psu temps only reach around 65°C at full load on my system, but thats with an underclocked and undervolted cpu (1.8ghz, 0.975V) and only a single tuner card.
now the only problem is my maxtor 10

it's neverending

cwl999 · Post by **cwl999** » Thu Mar 03, 2005 2:52 am

I spent last night tweaking the system.

Attached the FanMate onto the CPU fan with QFan enabled. Got Prime95 warming the system up and found that temps only 1-2c difference under load between min/max fanmate. The noise improvements between min/max was fairly pronounced, but quiet in both cases

Attached the PSU fan to the chassis plug with QFan enabled. VERY quiet when idling along. Once I cranked Prime95 into gear, the system started revving. Temps was 62 CPU, 52 MB. ~HOT~ but not toast, bit worried about the MB. The PSU exhaust was hot and I s'pect a little lacking in CFM.

I would recommend against attaching the the PSU fan to a QFan plug, mainly because the speed is based on the CPU/MB (???) temperature and not the PSU. Also once you stop burning, both fans slow down fairly quickly, the CPU dropped in temp but the MB stayed.

I've got my hands on a Panaflo 80x15 (thanks dorothy) and it's definately a lot quieter than the PSU fan (obviously less CFM). Will try plugging that into the PSU internal fan plug and see how it goes.

I also found that the CPU fan had a minor but annoying clicking. I sorted this out by taping the fan with some electrical tape and hence putting a minute ammount of isolation.

cwl999 · Post by **cwl999** » Thu Mar 03, 2005 3:22 am

How did you undervolt the Pundit-R? and what are you using to measure the PSU temp?

GrahamGarside · Post by **GrahamGarside** » Thu Mar 03, 2005 10:10 am

when you attach the psu fan + line to a 5V and leave the ground attached to the psu fan line it still controls the speed of the fan according to the psu temp, but can only reach a max of 5V but usually hovers lower.
I measured the temp using a temp probe from a fan controller/temp sensor in a nother system, I put the probe in the pundit psu on one of the heatsinks.
it just about runs at tolerable temps when it has a good flow of air, but without case modifications it wouldn't be safe.
I'm undervolting/underclocking by shorting out pins in the cpu socket. Shorting the 2 BSEL pins sets it to 400mhz instead of 533mhz (pins AD5&6) and to get 0.975v I shorted 2 VID pins together (pins AE1&2 which are VID 4 and 3)

cwl999 · Post by **cwl999** » Wed Mar 09, 2005 3:03 am

I've installed the Panaflo 80x15 in place of the orig PSU fan and attached it to the PSU's internal fan connector.

Everything seems fine and the system can Prime for hours.

My temps are now stable at CPU 60 MB 49 at load and CPU 45 and MB 47 idle. I don't think I need to do much more other than test the temps whilst horizonal.

I'll also see what the HD temps are like...

GrahamGarside · Post by **GrahamGarside** » Wed Mar 09, 2005 6:21 am

I put a standard 80x25mm fan in by cutting the top of the psu case off and then screwing it back on, it leaves about a 4mm gap between the top and the back where the fan is but it works

HD temps are a bit of a problem for me, my maxtor 10 reaches 60°C