powernow-k8 woes -- need help diagnosing intermittent failure

[John Belmonte <john@neggie.net>]

I'm having a hard time diagnosing a powernow-k8 problem.  It works fine
for several hours of power throttle stress testing, but eventually the
following error appears:

  kernel: powernow-k8: detected change pending stuck
  kernel: powernow-k8: transition frequency failed
  kernel: powernow-k8: failing targ, change pending bit set

After this failure, any further transition request yields:

  kernel: powernow-k8: failing targ, change pending bit set

which effectively renders power throttling unusable on my system.

I've tried two different brands of motherboard with the same Via
chipset, and see the same failure.  However, if it's a chipset problem,
I'd expect to see similar problem reports from other users, but I can't
find any.

A call for help: if you have the Via K8M800 or K8T800 chipset, or
specifically the DFI K8M800 or Chaintech K8M800 motherboard, and can
either confirm or deny this power throttling problem, please contact me.
 Even if you have a different chipset but the same CPU, and can claim
that powernow-k8 runs flawlessly, I'd like to hear it.

Any other ideas on how to diagnose this would be appreciated.

* motherboard: DFI K8M800 (Chaintech K8M800 has same failure)
* kernel: stock 2.6.13-rc4 (tried several other versions)
* CPU: Athlon 64 2800+, socket 754, stepping 10
* memory: tried Ultra and Viking PC3200 DDR 400MHz

--John