Things I tried and noticed that

[Amenas]

No idea why in the world how difficult it should be not to have the option. The only answer am getting is why do you wanna do this why lose 50% lose performance. 

Calculating this is not true even if the facts say 50% lose also make computer better in other parts.

*Battery

* You still got performance you don't need it to go 100%

Even if the CPU state (idle) says other wise of using all those hyperthreding when necessary. As long the thing is active and uses only when it feels like or what you are doing with computer  it's not woth it. CPU cores is all you need. 

In short way to say it hyperthreding disabled save alot of more then qhen it's enable or idle

[itsmyname]

> There is only one core ( e.g. single core cpu) which is at full utilization.

I disagree.

The CPU (Central Processing Unit) is one PHYSICAL component. 

Inside that CPU, you might find one, two, four, or eight cores -- replications of the same circuits.

Compare to buying an automobile. You purchase one, and it may have one seat (Formula One) or two seats (Ferrari as seen on "Magnum P.I.") or four seats (the soccer-mom's SUV). 

You are partially correct, the "extra" circuits provide a "virtual" core to Windows. When Windows queries the motherboard, the CPU may state "two cores, with zero (or one) hyperthread per core".  Windows treats each "virtual" code as being able to do the same work as the "real" core, and distributes the tasks requiring work over all the cores -- both "real" and "virtual".

By disabling hyperthreading, you are limiting the CPU to HALF of the total processing-power that it can provide.  Fortunately for you, your "gaming" program runs at an OK level when only HALF the cores are functioning.

Search online, to find any of the "CPU Benchmarking" tools, and run it, with hyperthreading disabled.

Enable hyperthreading, and rerun the tool. Compare the results, to show that only HALF of the CPU was actively being used. 

[Amenas]

You are right about cores and stuff but that line you said after.

-> By disabling hyperthreding, you are limiting the CPU to HALF of the total processing-power that it can provide.  Fortunately for you, your "gaming" program runs at an OK level when only HALF the cores are functioning.

That is why and no it's not forunatetly for me or anyone.

the good reason of doing this part disable it save power  battery and time of your laptop. you won't lose much if enable then disable.

I know why you wondering why why why disable why cons and stuff but it's not about that. It's all about the option for it and ability to disable or enable at anytime.

There is no better answer as how logic it is.

[itsmyname]

Take a look at "Device Manager" on your computer, to see something like:

What do you see on your computer?

My computer has 1 CPU chip, with 2 cores, with 2 threads per core, i.e., 4-way processing.

The "dispatcher" code within the heart of Windows spreads processing requirements over all 4 available processors, all the time, not, as you claimed, only when a core is "busy".

[Amenas]

I can see that your confused. I believe we are talking about two different things here. 

You are saying that 1 of 4 cores as in your picture has the amount of threads on each core. 

i'm talking about the option to available of disable hyperthreding in order to save laptop battery power cuz you don't normally need them necessarily. 

Enable this option when you open BIOS. Easy! 

[itsmyname]

>  You are saying that 1 of 4 cores as in your picture has the amount of threads on each core. 

Not, you are misunderstanding what the image shows. 

That computer has 1 CPU, with 2 cores, with 2 threads per core, 

but Windows treats all 4 threads equally -- when a task wants to use CPU resources, Windows selects a thread that is "waiting for work", and assigns that task to the "available" thread. All 4 threads are equally fast, and each thread can handle whatever task that is dispatched to the thread.

> i'm talking about the option to available of disable hyperthreading in order to save laptop battery power 

While that "trick" may have worked many years ago, a modern CPU and motherboard will adjust itself, to run at only the necessary speed.  Example:

You can see that the "speed" of each core can be different, thus conserving battery-power until really needed.  The above image was taken from a different computer, with 1 CPU and 4 cores and NO hyperthreading, but the principle applies -- namely that "manually" doing what the motherboard can do more quickly and more dynamically is not going to achieve what the computer can do, without your "assistance".

Short answer: enable hyperthreading, and let the motherboard do what it does best.

Enable this option when you open BIOS. Easy!