CPU Power saving tactics

[mikeymikec]

I inadvertently ended up with a Phenom II X6 recently (http://forums.anandtech.com/showthread.php?t=2209714&highlight=). I do a bit of gaming (StarCraft 2 and Arkham City being the most demanding ones), but largely CPU time is spent idling and with basic apps.

I'm running Win7 HP 64-bit SP1 with Windows's "balanced" power mode, and I can confirm that the processor is clocking down when idle. I'd like to save power and waste heat output where conveniently possible.

1) I've read about processor core parking in Win7, but from what I can see my processor doesn't have any parked cores, ever (looking in Performance Monitor in the CPU tab). Is this a processor-specific feature, can the Phenom II do this? Do I need a more expensive version of Windows for this feature to work? Can I get this to work on my system?

2) I'm considering disabling the core unlocking on my processor so it goes back to an X4, however I'm wondering whether core voltages alter or general power usage if I were to do this. I can monitor the overall system power usage, and I haven't yet checked it since the processor upgrade, so I can play around with this myself but I wondered if anyone knew the answer already.

2a) I assume that I can core unlock and re-lock whenever I like? The only thing I wonder about is whether Windows would "detect too many hardware changes" and ask me to re-activate it. I'm using a legit copy but I've heard of someone reactivating their licence too many times (ie. more than a hundred in their case), and don't see the point in risking it by messing around.

 

[superccs]

I have tried disabling cores on my x6 and temps do not change at all. There is an article online some where that goes through this whole experiment. The x6 power management is pretty good.

 

[ThatsABigOne]

You are going to be saving 2 to 5 dollars a month at most, which is, in my mind, not worth the pain of trying to configure the computer save as much power as possible.

 

[greenhawk]

2) I'm considering disabling the core unlocking on my processor so it goes back to an X4, however I'm wondering whether core voltages alter or general power usage if I were to do this. I can monitor the overall system power usage, and I haven't yet checked it since the processor upgrade, so I can play around with this myself but I wondered if anyone knew the answer already.

not worth the effort. Current CPUs that can idle have very little difference at idel power levels when the cpu core count changes (and nothing else). Only difference is when under load, but then the cpu is doing something faster than if it had less cores.

You could set the windows power mode to "power saving" (below balanced) and it should disable turboing and even run a max speed lower than the cpu's spec. It might save power, but it will definitly make processing based tasks take longer to complete.

 

[KingFatty]

I have the same motherboard you do, and I think I remember seeing something in the bios about selectively disabling cores, per core, at the bios level.

Also, instead of turning on the mechanical core unlocking switch on the mobo, you can instead turn off that switch and use the bios to unlock/lock (the only difference being that if you reset the bios, the computer will forget the setting for your core lock vs unlock, whereas if you use the mechanical switch, the computer will "remember" that you wanted to keep the cores unlocked). The way I see it, it's more control/flexibility if you use the bios settings rather than the mechanical switches, because bios resets are rare. But if you give the computer to your grandma, maybe use the switch to make sure all cores remain unlocked.

 

[Arkadrel]

@mikeymikec

Download K10stats

install it, make a shortcut to your start menu / startup folder.

open up the short cut and add:
-lp:1 -ClkCtrl:2 -StayOnTray -nw


That will make it start up windows, load K10stats, automatically, and have it stay in tray mode
(without a window pop-up when launched).
Lp means Load profile 1, and I forget what clkctrl 2 does atm.




Anyways, now you want to find the lowest stable voltage, your CPU can run (stable) at.

What you do is you "lock" your cores to the lowest speed setting and voltage. And you run stablity tests, once your happy with the results your done. Keep lowering until you get lowest possible stable result.

Then unclick the "lock", and now when your idleing, your doing so useing as little power as possible
(when your doing demanding stuff, it ll jump back to normal speeds).





***** with the Llano, some have reached more than 30% power reductions on the CPUs, while still running stable (simply because they ship with higher than needed voltage). Fine tuneing the power management with K10stats, can be quite usefull for laptops ect (longer battery life, with lower power use).

No reason not to do it with a desktop either though.


@mikeymikec

forget about disableing cores. Play around with voltages at idle mode, and find lowest stable ones.

 

[podspi]

The X6's don't have power gating, so I don't think (someone correct me if I'm wrong) you can turn them off in the literal sense anyway.

I'm sure turning them on uses some marginal amount of power, but if they're running idle it probably isn't that much. If you enable CnQ, and let the computer sleep when it's idle, I'd say you're 90% of the way to making all the tweaks you need.