[vdr] MSI MS-6215

Nicolas Huillard nhuillard at e-dition.fr
Wed Mar 23 13:03:31 CET 2005


jori.hamalainen at teliasonera.com a écrit :
>>The heat sources are the processor, the HDD and the DVB card 
>>(more if it is a full-featured one). The noise sources are 
>>the power supply (because this is the only one to the air out 
>>of the case) and the heatsink on th processor.
> 
> HDD is also a noise source. Proper rubber blocks can eliminate
> the noise conducted to the pc case and to your ear.

You're right, but I tend to now take HDD as near-silent, specially 
Seagate ones. There are two sources of noise : rotation + head 
movements. Seagates have both really low. Maxtor ahev low 
rotational-noise, but high head-movement noises, which are transmitted 
to the case.
Rubber blocks are a good idea. I also suspended HDD with textile rubber 
bands. Take care of the heat in this case.

> There are fan controllers available at shops. They start fan with
> 12V/no modulation, to make them rotating for sure, and then slows
> RPM down with much better way than resistor. Electric motors can
> and should be guided with pulse width modulation (RC models uses
> this, try searching "rc electronic speed controller").

This is also implemented in some hardware monitor chips, and known as 
PWM (pulse width modulation), and drivable using lm_sensor under linux. 
Really neat, but often not connected on the motherboard... I know that 
it exists on the chips on the Via EPIA M series, but not usable. What a 
pity...

>>>Finally, does anyone have any good ideas to minimise dust entry to the 
>>>machine other than putting the machine inside a cabinet.
> 
> Dust covers which are sold or shred a vacuum cleaner bag as a DIY project.

I tried this, but airflow is very impacted. It's better to have 
naturally low airflow (low fan speed) than to put a barrier on the path 
(air will pass elsewhere, and will accumulate dust where you don't 
expect it : in the DVD-tray opening, near the connector palates, etc.)

> Many HDD's can be 'underclocked'. 7200rpm disks can made to perform like 
> 5400rpm one. Check "hdparm -B" for APM support. Check "hdparm -M" for
> acoustic management support.

Acoustic management is really impressive on Maxtor, but the result is 
much noisier than Seagate. Head movements are simply smoother and a 
little slower, which increases latency (not a problem with huge files 
like VDR handles)

> Also HDD doesn't need to be running all the time, if your VDR is powered
> 24/7. Check noflushd for this. Works better than plain "hdparm -S".

There is also a laptop-mode included in kernel 2.6. You simply set the 
timeout after which dirty block are written to disk. This lets the time 
to APM to spin down the HDD. Take into account that the spin-up will 
take seconds and reduce the HDD lifetime...

-- 
NH



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