diff --git a/share/man/man4/acpicpu.4 b/share/man/man4/acpicpu.4
index 262c269e0a05..f79a034e2da2 100644
--- a/share/man/man4/acpicpu.4
+++ b/share/man/man4/acpicpu.4
@@ -1,4 +1,4 @@
-.\" $NetBSD: acpicpu.4,v 1.17 2010/08/27 18:05:16 wiz Exp $
+.\" $NetBSD: acpicpu.4,v 1.18 2010/12/20 08:33:09 jruoho Exp $
 .\"
 .\" Coyright (c) 2010 Jukka Ruohonen <jruohonen@iki.fi>
 .\" All rights reserved.
@@ -24,7 +24,7 @@
 .\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 .\" POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd August 27, 2010
+.Dd December 20, 2010
 .Dt ACPICPU 4
 .Os
 .Sh NAME
@@ -294,8 +294,20 @@ Furthermore, in the unlikely case where both
 .Nm
 and
 .Xr ichlpcib 4
+or
+.Xr piixpcib 4
 provide support for P-states,
-either one but not both may be used.
+the PCI-based interfaces should not be accessed due possible race conditions.
+.Pp
+All relatively new x86 systems should prefer
+.Nm .
+The options noted above are provided for legacy systems.
+The P-state support provided by
+.Dv ENHANCED_SPEEDSTEP
+and
+.Dv POWERNOW_K8
+are known to be either problematic or
+entirely dysfunctional with new x86 processors.
 .Sh SEE ALSO
 .Xr acpi 4 ,
 .Xr acpitz 4 ,