Gentoo MythTV

29. 08. 08

cooling the c3 in a small htpc case

Filed under: Main — Tags: , , — niko86 @ 19:19

as mentioned in an earlier post the c3 becomes very hot.
i bought the enzotech cnb-r1 mentioned before (click)
running with a fan it is a little bit better, but while testing with stress (a test tool, app-benchmarks/stress) the c3 reached about 85 °C which is the maximum temperature referring to the data-sheet.
so i stuck another 40mm fan between the northbridge and the cpu cooler to blow the hot air from the cpu cooler to the hard disk where the “exhaust” fans are located.
this did not “solve” the problem but now i can close the case and the CPU temperature stays below 80°C.
if the system is in idle (also while watching videos or tv), the temperature immediately drops to 40°C and stays there.
It is strange indeed, the Temperature of the CPU only goes up significantly if the load is higher than 3.00, below that there is no problem, so for the every-day-use of the frontend it will be good enough.

22. 08. 08

getting my hands dirty!

Filed under: configuration — Tags: , , , , , , , , — niko86 @ 1:01

after several hours of trying different myth distributions and livecds, i got to the point where i just put the gentoo minimal install cd into the drive and start compiling away.

unfortunately the c3 i got on the m9000 board is an older one which labels itself as i686 but is missing the cmov instruction.
that’s why most of the distributions won’t work because they can’t tell that it is in fact an i586 processor and is lacking the cmov instruction.
so all you get are some nasty segfaults…

so got back to good’ol gentoo:
this is what i used for CHOST and CFLAGS:


CHOST="i386-pc-linux-gnu"
CFLAGS="-mtune=i586 -march=c3 -m3dnow -mmmx -Os -pipe \
-fomit-frame-pointer

just specified mtune as well because some people reported about some nasty errors where the compiler looked for the mtune or the deprecated mcpu flag, didn’t find it and just assumed an i686 which resulted in…. you guessed it: segfaults

i will put the kernel config for the ezra c3 m9000 board online later so if someone comes here while searching for this it will save them alot of time….

it actually was not that easy to find out that the older ezra / samuel c3’s do not support cmov instructions but the nemehia and newer c3’s do so.
the fact that a sticker on my board said “nemehia” did not make it any easier.

another conclusion i’ve come to is that the morex cubid 2600 is not a particularly good case when it comes to cooling and air circulation.
it has some air intakes on both sides and two 40x40mm fans sucking air out behind the harddrive mount, but the mounting bracket for the pci card and the slot for the slim drive in combination with the IDE cables are doing a good job of preventing some good airflow.
after some hours of compiling, i measured 70°C CPU and 50°C Harddrive Temperature, the Northbridge was too hot to touch and so was the RAM.

So i quickly “engineered” a new cover for the case out of some cardboard, did a 120x120mm cut out and put a nice 120mm fan in it.
“mounted” the cardboard cover instead of the original case cover and now i got some good airflow, i also did disable the 2 40×40 fans to stop the noise they where making.

well, im right at compiling the basic needs of the system and all i can say is: roughly 1ghz and a tiny Cache are not exactly speeding up the process of compiling.
it takes ages to compile….

hopefully this baby will be capable of being a nice frontend….

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