AM3+ CPU & Motherboard - how does APM help ?

[davexnet]

Hello -
I'm trying to get a picture of the pros and cons of this being active in the BIOS.
The Bios setup says that APM is disabled if you manually lower the CPU voltage,
I tried it because in some situations the CPU does run cooler this way. What am I losing by APM
being inactive ?

Here's my original thread that I did not get any responses.
https://forums.anandtech.com/threads/cpu-voltage-heat-apm-on-budget-board.2512324/

If anybody has a perspective on this, please post
Dave

 

[Ketchup]

APM works with the chip's speed technology to allow the chip to run at a lower speed and use less power when the chip isn't under full load. When encoding video, for example, all 4 of those cores are going to run full speed and full voltage, so the APM isn't going to do anything vs not using it. In this case, running lower voltage would allow the CPU, and therefore the entire system to put out less heat. Running full speed and full voltage when the system isn't doing anything will keep the computer a little warmer during off times though, so you might want to get into a rhythm of turning it off and off based on what you are doing if the heat output is that important to you.

 

[davexnet]

I checked the CPU tab on CPU-Z and even with the voltage manually lowered in the BIOS and presumably APM off,
CPU is still throttling down . I see the CPU multiplier jumping between 7x and 19x (and one in the middle somewhere)
as the demand changes,.
Thanks for your explanation, it's a good way to get your head around it . Ambient temps and humidity been very high
so that may be partially to blame no a/c in the apartment. Thank goodness it cools down in the evening.
Based on your write up, I did not expect to see throttling still active.

 

[Ketchup]

I don't follow AMD like I used to, so this could just be something on top of, but separate from, the cool 'n quiet they used to have. And that is a good thing, as you have found, since it allows you to lower voltages while retaining the slower speeds offered when not under load.

 

[davexnet]

Appreciate your comments. One last thing, I see no ill effects from lowering the voltage, to me it can only be a good thing,
I'm going to leave it for a while as I set it and see if there are any performance issues - I have not noticed anything so far.

It seems as if there is some leeway, and the default setting is conservative. On mine the default is 1.250 V and can be lowered
in 0.025 increments. I brought it down (as an experiment) to 1.175 V and it still seems fine. I've settled on 1.225 V and while close
to default, runs cooler under load.