low speed fan on CPU fan header has weird reading?

freshy98 · Jun 21, 2003

have a big *** Delta fan to cool my Vapochill radiator and have put the fan reading wire to the CPU fan header.
On my old K3T Ultra it reported the fan speed correctly, but on my Abit NF7-S rev 2.0 it reports speeds between 2392rpm and 337500prm. quite a difference here ;-) the max speed of the fan is 3000rpm.

does anybody know of this problem and maybe how to fix this?

I have not yet tried putting the wire on on of the other 2 fan headers to check if they do sensor the correct rpm speed though.

schismspeak · Jun 21, 2003

What are you using to report the rpm?(program)
In MBM5 you can change the type of fan it is monitoring so it will show the correct reading.

freshy98 · Jun 21, 2003

I am using MBM 5.5.3.0 (latest to date).

I also forgot to mention something. The reading are the same in the BIOS as well as with MBM5.
when I enter the health page of the BIOS, the computer locks up in seconds. if I don't enter the page there is no problem with the rest of the pages.

MBM5 does not lock up nor is windows.

schismspeak · Jun 21, 2003

Hmm, I dunno; did you try a different header yet?

freshy98 · Jun 22, 2003

no, not yet. I'm with my parents this weekend. will try it tonight or tomorrow when I'm back where I live.
will let you know here.

freshy98 · Jun 24, 2003

well, I put the wire on a different header and still I get these weird readings. sometimes however I do see the correct rpm speed, but the rest is way above that.

I dunno, but it seems that Abit screwed something up with the sensor reading in the BIOS.

arabarabian · Jun 24, 2003

Maybe over time the fan speed sensor has gotten messed up. It would be better to think it is your fan and not the motherboard.

Thank You,
Daniel

josi · Jun 24, 2003

Maybe this information from the MBM help can help you:

Fan Dividor
Default this value is 4, this means that fans as low as 1300 rpm will show up, the lower you set this value the more accurate the fan RPM will be, but if you set it to low your fan might not show up. Check the little table below:

Dividor Minimal RPM Highest RPM Use in most cases for:
1 5300 1350000
2 2650 675000 CPU Fans
4 1325 337500 Case Fans
8 662 168750

freshy98 · Jun 24, 2003

arabarabian said:
Maybe over time the fan speed sensor has gotten messed up. It would be better to think it is your fan and not the motherboard.

Thank You,
Daniel

that could be right, but then it would have happend right between connecting it from the MSI KT3 Ultra towards the Abit NF7-S rev 2.0
I think that's a bit to big of an coincidence (spelled wrong, I know)

freshy98 · Jun 24, 2003

josi said:
Maybe this information from the MBM help can help you:

Fan Dividor
Default this value is 4, this means that fans as low as 1300 rpm will show up, the lower you set this value the more accurate the fan RPM will be, but if you set it to low your fan might not show up. Check the little table below:

Dividor Minimal RPM Highest RPM Use in most cases for:
1 5300 1350000
2 2650 675000 CPU Fans
4 1325 337500 Case Fans
8 662 168750

josi, on my KT3 Ultra I also run MBM5 and it was just fine. also, in the health page in the BIOS the speed is already messed up. hence, the PC even completly hangs when I enter that page for more than 1 second.
that is why I believe it's not just MBM5.

josi · Jun 25, 2003

The BIOS programs the initial fan speed divider value at the startup, if this value is too low, fan speed will not be correctly shown even in the BIOS, so maybe it is worth to try to adjust it in the MBM.
Another possibility - too low input voltage from the fan speed sensor, especially if you use a rheostat to limit fan speed.

low speed fan on CPU fan header has weird reading?

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