Index: sys/dev/amdtemp/amdtemp.c
===================================================================
--- sys/dev/amdtemp/amdtemp.c
+++ sys/dev/amdtemp/amdtemp.c
@@ -111,8 +111,16 @@
 
 /*
  * Reported Temperature, Family 17h
+ *
+ * According to AMD OSRR for 17H, section 4.2.1, bits 31-21 of this
+ * register provide the current temp.  bit 19, when clear, means the
+ * temp is reported in a range 0..225C (which should be 255C), and
+ * when set changes the range to -49..206C.
  */
-#define	AMDTEMP_17H_CUR_TMP	0x59800
+#define	AMDTEMP_17H_CUR_TMP		0x59800
+#define	AMDTEMP_17H_CUR_TMP_RANGE_SEL	(1 << 19)
+#define	AMDTEMP_17H_CUR_TMP_RANGE_OFF	490
+
 
 /*
  * Thermaltrip Status Register (Family 0Fh only)
@@ -591,13 +599,15 @@
 amdtemp_gettemp17h(device_t dev, amdsensor_t sensor)
 {
 	struct amdtemp_softc *sc = device_get_softc(dev);
-	uint32_t temp;
+	uint32_t temp, val;
 	int error;
 
-	error = amdsmn_read(sc->sc_smn, AMDTEMP_17H_CUR_TMP, &temp);
+	error = amdsmn_read(sc->sc_smn, AMDTEMP_17H_CUR_TMP, &val);
 	KASSERT(error == 0, ("amdsmn_read"));
 
-	temp = ((temp >> 21) & 0x7ff) * 5 / 4;
+	temp = ((val >> 21) & 0x7ff) * 5 / 4;
+	if (val & AMDTEMP_17H_CUR_TMP_RANGE_SEL)
+		temp -= AMDTEMP_17H_CUR_TMP_RANGE_OFF;
 	temp += AMDTEMP_ZERO_C_TO_K + sc->sc_offset * 10;
 
 	return (temp);