Tom's Hardware > All Reviews > How To > Tweaking & Tuning > Updated: Tuning Cool'n'Quiet: Maximize Power And Performance

Voltage Ramp And Power Consumption, Continued

07:10 - Tuesday 9 March 2010 by Arnawa Widagda

Phenom II X3 710

Clock	Core and Northbridge Voltage	Idle	Load
1.6 GHz	0.925V	59 watts	78 watts
1.7 GHz	0.950V	67 watts	81 watts
1.8 GHz	0.975V	68 watts	84 watts
1.9 GHz	1.000V	68 watts	86 watts
2.2 GHz	1.035V	70 watts	89 watts
2.3 GHz	1.050V	72 watts	92 watts
2.4 GHz	1.075V	74 watts	94 watts
2.6 GHz	1.100V	76 watts	99 watts
2.7 GHz	1.125V	78 watts	101 watts
2.885 GHz	1.175V	83 watts	110 watts
2.940 GHz	1.200V	84 watts	114 watts
3.060 GHz	1.250V	92 watts	120 watts

Just a reminder: we had to overclock the HT bus to 245 MHz (though we'd lock the multiplier at 7x) to get above 2.6 GHz. This processor is not a Black Edition model. The resulting clock rate increase is not gradual; this would explain the relatively greater rise is power consumption when going from 2.7 GHz to 2.895 GHz.

Unlike the Athlon X2 7750, we're not seeing any “free MHz” here. If you want to push power consumption as low as possible, 1.6 GHz is the only choice. This should be the lowest idle p-state, if possible. You can choose 1.7 GHz and 2.2 GHz as intermediate p-states, with the performance p-state set at 2.6 GHz.

If you're into overclocking, 3.06 GHz still makes sense. You don't even have to change p-states settings (except for voltages). The intermediary and idle p-states are already optimal (2.327 GHz, 1.715 GHz, and 980 MHz).

Let's compare these numbers with the default settings. At 3.06 GHz, we can still get about the same level of load power consumption. After all, we're still using the same voltage. However, idle power consumption is higher by about 10 watts (92 versus 81 watts). That difference stays the same if we choose 2.7 GHz @ 1.15V as the idle p-state.

Phenom II X4 945

Clock	Core and Northbridge Voltage	Idle	Load
1 GHz	0.900V	72 watts	88 watts
1.9 GHz	0.925V	73 watts	90 watts
2.5 GHz	0.950V	74 watts	92 watts
3 GHz	1.100V	80 watts	120 watts
3.13 GHz	1.125V	85 watts	137 watts
3.25 GHz	1.150V	86 watts	145 watts
3.38 GHz	1.200V	90 watts	158 watts
3.5 GHz	1.250V	96 watts	177 watts

As with the Phenom II X3 710, we had to overclock the HyperTransport interconnect to 250 MHz to get above 3 GHz; this is not a Black Edition processor. Hitting power consumption levels below 70 watts is not possible (yet) with the Gigabyte GA-MA790GP-DS4H. With that in mind, 1.9 GHz seems to be the best choice for the idle p-state, or at least the second intermediary p-state. The first intermediary p-state can be set at 2.5 GHz with the performance p-state at 3 GHz.

We were unable to reach stability above 3.5 GHz, even at 1.35V. So, the highest setting we're using is what we can achieve with 1.25V (3.5 GHz). This setting isn't really ideal from a power consumption point of view, since the increase in voltage causes power consumption to jump. The optimal setting is really just 3 GHz, the default clock rate for this processor. If you're overclocking, you might get away with 3.25 GHz, since the difference is minor (5 to 10 watts).

With the GA-MA790GP-DS4H, we didn't have to boost voltages for lower p-states when overclocked. That means you can use 2.5 GHz and 3 GHz for intermediary p-states, with 2 GHz as the idle p-state and 3.5 GHz as the performance p-state. Idle power consumption is about the same when you overclock with this motherboard.

Since we're using almost the same voltage at 3.5 GHz (1.25/1.25V compared to the default 1.35/1.1V), we were able to get slightly lower power consumption numbers than default (96/177 watts at 3.5 GHz compared to 103/177 watts at 3 GHz). At 1.15V we can still hit 3.125 GHz. If you want to maintain idle power consumption, use 2.5 GHz @ 0.95V. Compare that setting to the default, 800 MHz to 2.5 GHz. That's quite a bit of difference.