What are C1 Transitions? How can I stop them?

[mfreeman]

I am running a new Dell Inspiron E1705 (Intel Core 2 Duo 2 GHz, 2G
RAM) that came with Vista Premium. Every few minutes, there is a
"hiccup" when playing MP3 files.

I ran the "Reliability and Performance Monitor" and found that when
the hiccups occur, there is a big spike in "C1 Transitions/sec." (from
zero to over 6,000) and a simultaneous dip in "C3 Transitions/sec."
from an average around 2,000 to zero. There are occasional C1 spikes
without a C3 dip and those don't seem to affect Media Player. This
would seem to indicate an issue related to CPU power states.

I am running on AC/Power in "High performance" power mode. It is set
with a minimum processor state of 100% and to never sleep or
hibernate. I also noticed a corresponding spike in the "dwm" process
CPU usage, so I disabled the Sidebar. "dwm" doesn't spike any more,
but the C1/C3 issues remains the same. I am running the machine
disconnected from any network when this occurs, and there are no other
apps active (other than Windows Explorer).

Does anyone else have this problem? Can anyone point me to a good
explanation of what C1 and C3 transitions are, how they interrelate,
and what OS settings can impact them?

Thanks,

Mark

 

[AJR]

One of the first returns by Google directs you to a TechNet explanation
site.