2 cores at 2.5ghz or 4 cores at 1.5ghz ?? which is better for saving power?

[Thunder_Ruler0]

I want to know what is the most efficient option to choose from when it comes to saving battery power on a laptop. I'm using a Intel core-i5 with 4 cores at 2.5ghx

 

Either changing it so that it uses only a certain percentage of the total CPU power (I have it at 1.5ghz max on battery) while still running it on ll four cores

OR limiting most of my used programs (like Chrome) to 2 core at full 2.5 GHZ while 

 

Is there any other options that you guys know of?

 

Edit:  Just to be clear, it's 2 physical core and 2 hyperthreading cores

[MegaVoltz]

I would set it to 2 cores at 2.5GHz. Per-core speed is probably better unless you do video editing or gaming.

[Blebekblebek]

I don't see how is that going to make any differences if your behavior using it doesn't change either.

Either option will makes your processor works almost 100% all the time.

 

Computer nowdays already can underclock it self when it's idle, specially laptop.

But maybe I'm wrong

 

 

[WereCat]

If you can then just undervolt the CPU and leave it on stock clocks.

[Thunder_Ruler0]

1 minute ago, Blebekblebek said:

I don't see how is that going to make any differences if your behavior using it doesn't change either.

Either option will makes your processor works almost 100% all the time.

 

Computer nowdays already can underclock it self when it's idle, specially laptop.

But maybe I'm wrong

 

 

what do you mean 100%? if I'm limiting it to 1.5GHZ it comes up to a max of 60% CPU utilization. And limiting half the cores would bring that around 50% most likely not including the turbo boost function of Intel CPU's

[Thunder_Ruler0]

1 minute ago, WereCat said:

If you can then just undervolt the CPU and leave it on stock clocks.

got any suggestions how I may be able to do that? Is it any different than just choosing the option rather than doing it in BIOS?

[WereCat]

1 minute ago, Thunder_Ruler0 said:

got any suggestions how I may be able to do that? Is it any different than just choosing the option rather than doing it in BIOS?

Do it in BIOS if you can.

Otherwise, try Intel Extreme Tuning Utility.

[Mira Yurizaki]

It really depends on what you do, but now and days, CPUs and OSes will park and adjust the core speed as necessary so it may be best to leave it alone.

[paddy-stone]

Agree with leaving it alone, it could end up eating more battery life if you change it, eg a task takes more time to run on a lower clocked CPU, that will also have screen on time as more not just the cpu time it took, that's my reasoning anyway.

[Thunder_Ruler0]

40 minutes ago, paddy-stone said:

Agree with leaving it alone, it could end up eating more battery life if you change it, eg a task takes more time to run on a lower clocked CPU, that will also have screen on time as more not just the cpu time it took, that's my reasoning anyway.

 

54 minutes ago, M.Yurizaki said:

It really depends on what you do, but now and days, CPUs and OSes will park and adjust the core speed as necessary so it may be best to leave it alone.

 Well lowering the CPU clock to a point that based on my daily usage it doesn't stutter or slow down, the reason why I chose 1.5GHZ...

 

Not to mention me keeping it to a limit keeps the CPU from heating up and ramping up the fan.

 

Also 'parking' the CPU is an option in power settings with the minimum percentage of the CPU you want to use. Keeping it down to 0% on battery and 100% plugged in on my case to constantly adapt to what I use.

 

but I see the reasoning for the screen on portion 

[Mira Yurizaki]

1 minute ago, Thunder_Ruler0 said:

 Well lowering the CPU clock to a point that based on my daily usage it doesn't stutter or slow down, the reason why I chose 1.5GHZ...

 

Not to mention me keeping it to a limit keeps the CPU from heating up and ramping up the fan.

Then tweak with the maximum processor state percentage in the advanced power options.

 

Don't do anything in the BIOS level unless you're fine with restarting the computer every time you want to modify your PC's performance for a specific use case.

[Thunder_Ruler0]

2 minutes ago, M.Yurizaki said:

Then tweak with the maximum processor state percentage in the advanced power options.

 

Don't do anything in the BIOS level unless you're fine with restarting the computer every time you want to modify your PC's performance for a specific use case.

that's what I've done, it's what I've been talking about this entire time :') I have it limited to 65% which is 1.5GHZ

[paddy-stone]

1 minute ago, Thunder_Ruler0 said:

 

 Well lowering the CPU clock to a point that based on my daily usage it doesn't stutter or slow down, the reason why I chose 1.5GHZ...

 

Not to mention me keeping it to a limit keeps the CPU from heating up and ramping up the fan.

 

Also 'parking' the CPU is an option in power settings with the minimum percentage of the CPU you want to use. Keeping it down to 0% on battery and 100% plugged in on my case to constantly adapt to what I use.

 

but I see the reasoning for the screen on portion 

If you don't do anything that CPU intensive, then it may be a good idea, was just saying that for anything intensive it may end up eating more battery because of having the screen on for longer etc. Try it and see is the only way to go really, if in your daily usage you notice it's actually using more battery that way, just chnage it back or make other changes.

I agree also that it might be better to just change the maximum % in the power options than to change it in the BIOS, at least it's more accessible to chnage it again of needed without having to restart etc.

[Mira Yurizaki]

8 minutes ago, Thunder_Ruler0 said:

that's what I've done, it's what I've been talking about this entire time :') I have it limited to 65% which is 1.5GHZ

Well then tell you what. Run your daily rigamaroll with 100%, then again at 65% and see what difference you'll get in terms of battery life and performance.

 

That's pretty much the only way you'll find your answer.

[Thunder_Ruler0]

22 minutes ago, M.Yurizaki said:

Well then tell you what. Run your daily rigamaroll with 100%, then again at 65% and see what difference you'll get in terms of battery life and performance.

 

That's pretty much the only way you'll find your answer.

I can do that easily, but this brings me back to my main question, is it better to reduce the total speed to 65% or 1.5ghz across all 4 cores, or just limit programs to 2 cores at 2.5 GHz?

[Mira Yurizaki]

2 minutes ago, Thunder_Ruler0 said:

I can do that easily, but this brings me back to my main question, is it better to reduce the total speed to 65% or 1.5ghz across all 4 cores, or just limit programs to 2 cores at 2.5 GHz?

And again, it depends on what you do and how you do it. I don't know what you do and how you do it, so I can't really answer this question with a degree of high confidence.

[SpaceGhostC2C]

2 hours ago, Thunder_Ruler0 said:

I want to know what is the most efficient option to choose from when it comes to saving battery power on a laptop. I'm using a Intel core-i5 with 4 cores at 2.5ghx

 

Is there any laptop i5 with four cores? Or is it a dual core with hyperthreading?

[Thunder_Ruler0]

Just now, M.Yurizaki said:

And again, it depends on what you do and how you do it. I don't know what you do and how you do it, so I can't really answer this question with a degree of high confidence.

Okay let me put it this way, this is the best way I can think to explain it. 

 

What would be better, using a 4 cylinder engine at half the power, or using a 2 cylinder engine at full? Yes I know it's unrelated, but would run off four cores in unison use more energy than just running off two? I know it depends on my usage, I get that, but I mean in general, just based on how much energy the CPU would use in the first place. 

 

I doubt "turning off" a core actually turns it off and cuts power to that part of the chip, but it does mean it's not being used. The clock speed  I can put on the CPU is 1.17GHZ across all cores, which means im sucking energy from all cores compared to if it was just two cores. 

 

Do you get what I mean? (English isn't my strong point so excuse any grammer)

[Thunder_Ruler0]

1 minute ago, SpaceGhostC2C said:

Is there any laptop i5 with four cores? Or is it a dual core with hyperthreading?

Forgot to add that, but it's 2 physical cores and 2 hyper threading 

[SpaceGhostC2C]

Just now, Thunder_Ruler0 said:

Forgot to add that, but it's 2 physical cores and 2 hyper threading 

Well, that matters because you only have two cores to feed, regardless of how many "logical cores" are reported to Windows.

 

Hence, the only thing you can do is disable one core or use both. You can also disable hyperthreading, with may save you some power consumption, but only if you are indeed running something tha spans over 4 threads. I wouldn't expect much of a gain from that if you are not using your CPU at close to 100% most of the times.

[Thunder_Ruler0]

1 minute ago, SpaceGhostC2C said:

Well, that matters because you only have two cores to feed, regardless of how many "logical cores" are reported to Windows.

 

Hence, the only thing you can do is disable one core or use both. You can also disable hyperthreading, with may save you some power consumption, but only if you are indeed running something tha spans over 4 threads. I wouldn't expect much of a gain from that if you are not using your CPU at close to 100% most of the times.

Okay, but is it possible to disable one physical core and keep the other two with one hyper threading and physical? So that I'm left with 2 still but physically just feeding 1?

 

I can see what you mean, but it just keeps going back to the 4 cylinders at 50% power versus 2 cylinders at full power sort of energy usage physiology. 

[SpaceGhostC2C]

Just now, Thunder_Ruler0 said:

Okay, but is it possible to disable one physical core and keep the other two with one hyper threading and physical? So that I'm left with 2 still but physically just feeding 1?

Yes, you can disable one core and keep hyperthreading enabled. You need to check your BIOS, though, as you may or may not have the option there. If you don't, you can always disable it in Windows.

Just now, Thunder_Ruler0 said:

 

I can see what you mean, but it just keeps going back to the 4 cylinders at 50% power versus 2 cylinders at full power sort of energy usage physiology. 

Yes, but you see, the analogy is not that good because you have to feed fuel to a cylinder in a working engine, whereas electricity doesn't work like that. It's more "on demand", if you will, and there is less correlation between the demand of one core and the others (you cannot have a cylinder go out of sync with the others, while CPU cores run at different speeds or go "parked" all the time).

[Mira Yurizaki]

Just now, Thunder_Ruler0 said:

Okay, but is it possible to disable one physical core and keep the other two with one hyper threading and physical? So that I'm left with 2 still but physically just feeding 1?

 

I can see what you mean, but it just keeps going back to the 4 cylinders at 50% power versus 2 cylinders at full power sort of energy usage physiology. 

Yes, but if you're on a laptop, probably not because system builders usually don't allow that level of control.

 

10 minutes ago, Thunder_Ruler0 said:

Okay let me put it this way, this is the best way I can think to explain it. 

 

What would be better, using a 4 cylinder engine at half the power, or using a 2 cylinder engine at full? Yes I know it's unrelated, but would run off four cores in unison use more energy than just running off two? I know it depends on my usage, I get that, but I mean in general, just based on how much energy the CPU would use in the first place. 

 

I doubt "turning off" a core actually turns it off and cuts power to that part of the chip, but it does mean it's not being used. The clock speed  I can put on the CPU is 1.17GHZ across all cores, which means im sucking energy from all cores compared to if it was just two cores. 

 

Do you get what I mean? (English isn't my strong point so excuse any grammer)

Well let's take some scenarios:

• From a pure, worst case standpoint, four cores at 1.5GHz is worse than two cores at 2.5GHz
• If you had a task that took say 1, 2, 3, and 4 seconds, the two cores at 2.5GHz is still better since the total run time is 4 seconds for four-cores at 1.5GHz and 3 seconds for two cores at 2.5GHz. This is a gross simplification, it does not account for any overhead involved with processing things such as task switching or grabbing data from cache.
• If you had tasks that all ran at nearly the same run time, then four-cores at 1.5GHz is better since two-cores at 2.5GHz does not have a theoretical performance to match four cores at 1.5GHz

Considering that a lot of tasks people do are idling and are usually more sensitive to clock speed than core count, then sure, two cores at 2.5GHz would be better.

 

However, again, modern CPUs and OSes can fine tune their performance needs, which includes parking CPU cores if the system feels it doesn't need the extra boost. So I don't feel there's any real value in manually adjusting anything.

 

But we're all talking theoretical here. A hypothesis is kind of useless without the experiment to test it.

[Thunder_Ruler0]

1 minute ago, SpaceGhostC2C said:

Yes, you can disable one core and keep hyperthreading enabled. You need to check your BIOS, though, as you may or may not have the option there. If you don't, you can always disable it in Windows.

 

Okay I will look into this then and see what I find out. 

1 minute ago, SpaceGhostC2C said:

Yes, but you see, the analogy is not that good because you have to feed fuel to a cylinder in a working engine, whereas electricity doesn't work like that. It's more "on demand", if you will, and there is less correlation between the demand of one core and the others (you cannot have a cylinder go out of sync with the others, while CPU cores run at different speeds or go "parked" all the time).

I think it's perfectly applicable minus the syncing part. Inside of Windows the CPU has a minimum clock that the user cannot go the past, in my case, I believe it's around 25% or 1.17GHZ like I mentioned before, anyways that means that there's still running to do whatever we throw at it, and is constantly receiving that energy (because windows really). That means I'm using energy while these physical cores are 'parked' it wouldn't matter if I wasn't doing anything with the system.  That's the part of the analogy. The more cores the more energy, and yes like I said, they use a lot less energy docked, but it's still 'on' which means using energy and sitting there. 

 

That's why im asking if whether or not disabling that one physical core would mean that it 'turns off' meaning that it receive (at least) the absolute minimum amount of energy which you cannot do in Windows since it's forced to run at 1.17GHz regardless. While the other cores are running at the efficiency threshold where they operate the best. 

 

(graph of the equation that is used to measure the correlation between CPU energy usage and Clock speed)