Xsensors report Vcore 1.01V for Opteron 285 @2.6Ghz on Kubuntu 8.10 and
cpus freeze. At 2.2Ghz (Vcore 0.94V), cpus do not freeze. My MOBO
is MSI K8D Master2-FAR (I know, too old to muck with, sigh...). Are
Xsensors reliable? AMD spec for Opteron 285 Vcore is 1.30-1.35V. Bios
reports Vcore as 1.29/1.34V @2.6Ghz (I have 2 CPUs). How do I raise
Vcore under Kubuntu? Also, Xsensors applet panel only shows one entry for Vcore and one entry for CPU Temp (should be 2 each?) The sensor chip
is reported as w83627thf.
Stuart

AFAIK, no; there are several problems. Some mobos use one channel (electrically) for parameter 'A' and some use the same channel for a parameter 'B'. Certainly on some older boards, when things were not so well standardised, channels could get interchanged. Also, some of the parameters are a little difficult to measure with the available (low cost) technology and the end result is that there can be offsets.

In general, if there is a disagreement between something measured at a higher level and what is measured in the bios, I would have more faith in what the bios says. I still wouldn't have absolute faith in the bios, essentially because there is an issue of definition. withe thermal drops across the material of the cpu, do you know exactly where the measurement is made? the same applies electrically; maybe it says Vcpu, but that will be a different value at the source of Vcpu for at the socket and that will be different from the value measured on the chip and in every case the meaasurement will be different if measured with respect to ground at the generating IC, from at the socket from on the chip near the pins to from on the chip in the cpu section.

Now, this wasn't such a big issue ~10 years ago when everything got a 5 volt supply and the currents were relatively low, but today it is a factor. The only thing that I can say is that if the number read in the bios is significantly out, they will add in a fiddle factor to correct it, so the bios reading is probably as good as it gets. Although it doesn't harm to check the heatsink temperature with an optical pyrometer, to check whether the bios value passes the 'sanity test'.

Use lspci to check your chip The kernel modules available affect the identification. I have a 2ghz twin core turion and I got no sense out of ubuntu. Install acpitools and then you'll get somewhere. It doesn't show voltage, but does show just about everything else. It's soo tricky here. There are C states for saving power which have the cpu in anything from slightly slower to suspended animation depending on the one used. They vary voltage. There's kernel schedulers and everything having fun here.

With 64 bit linux, you hit the pain barrier fairly quickly. At least I did.

The lm_sensors site recommends that you fine-tune for your specific hardware by editing the configuration file.

Probably Xsensors is just wrong, but either way are you sure your PSU is powerful enough, I say use a calculator to estimate power usage, and if your PSU can handle it:
http://www.extreme.outervision.com/p...ulatorlite.jsp

You would do that in BIOS.

As well as the BIOS you have Kernel schedulers, and ACPI affecting vcore


Are you using conservative scheduling? ACPI can also do things. If it goes to a deep C-state a cpu is basically off. And there's only one power line in. I have the opposite problem - low battery life.