in bios, there is hypertred option, if i turn off, what will happen and if i keep turn on , what will happen?

Hyper-Threading (HT), or Simultaneous Multi-threading (SMT) as it’s known on AMD processors, is a technology that allows a single physical CPU core to appear as two “logical” cores or “threads” to the operating system. The idea is to make more efficient use of the CPU’s resources.

Let’s break down what happens when you turn it on or off:

If you turn OFF Hyper-Threading:

1. Fewer Logical Cores: Your operating system will see only the number of physical cores your CPU has. For example, an Intel i7 with 4 physical cores would appear as 4 cores/4 threads instead of 4 cores/8 threads.
2. Potential for Higher Single-Core Performance (in some specific cases):
   • Since each physical core is now dedicated to processing only one thread at a time, it doesn’t have to share its resources (like execution units or cache) with a second “logical” thread.
   • This can theoretically lead to slightly better performance per individual thread, especially in very CPU-intensive tasks that are not well-optimized for multiple threads (e.g., some older games or specific single-threaded applications).
3. Reduced Multi-Threaded Performance (for most modern tasks):
   • For applications designed to use multiple threads (like video editing, 3D rendering, heavy multitasking, modern games that utilize many cores), disabling HT will generally reduce overall performance. You’re effectively cutting the number of available threads your CPU can process concurrently in half.
4. Lower Power Consumption and Heat: With fewer active “logical” threads, the CPU generally consumes slightly less power and generates less heat. This can be beneficial for laptop users or those trying to achieve higher stable overclocks, as it provides more thermal headroom.
5. Potential for Stability with Older Software: Very old or poorly optimized software/games might sometimes exhibit issues (like stuttering or crashes) when Hyper-Threading is enabled because their scheduling logic can get confused by the “virtual” cores. Disabling HT can sometimes resolve these niche compatibility problems.

If you keep ON Hyper-Threading (the default and generally recommended setting):

1. More Logical Cores/Threads: Your operating system will see double the number of threads as physical cores (e.g., 4 physical cores become 8 logical threads).
2. Improved Multi-Threaded Performance (for most modern workloads):
   • This is the primary benefit. When one logical thread on a physical core is waiting for data (e.g., from memory), the other logical thread can utilize the idle execution units of that same physical core. This allows the CPU to process more instructions simultaneously, increasing overall throughput.
   • This is particularly beneficial for:
     • Heavy Multitasking: Running many applications at once.
     • Content Creation: Video editing, 3D rendering, CAD, compiling code.
     • Modern Games: While some older discussions suggested disabling HT for gaming, modern games and operating system schedulers are generally optimized to utilize HT effectively, often leading to better average FPS and improved 1% lows (smoother gameplay).
     • Virtual Machines: Running multiple virtual machines benefits greatly from more apparent “cores.”
3. Increased Power Consumption and Heat (slightly): Because the CPU is working more efficiently and utilizing more of its resources, it will generally consume slightly more power and generate a bit more heat.
4. Potential for Minor Latency: In some very specific, highly optimized single-threaded workloads, the overhead of managing two logical threads on one physical core could introduce a tiny bit of latency compared to a single thread having exclusive access. However, this is usually negligible for general use.

Conclusion:

For most modern users, especially those who multitask, game with recent titles, or perform productivity tasks like video editing or software development, keeping Hyper-Threading ON is generally recommended. It leads to better overall system responsiveness and higher performance in multi-threaded applications.

You would typically only consider turning it off if:

• You encounter specific, rare compatibility issues with very old or niche software.
• You are trying to achieve maximum possible single-core performance (e.g., for certain competitive benchmarks) and are willing to sacrifice multi-threaded performance.
• You are dealing with extreme thermal constraints and need to reduce CPU heat generation as much as possible, even at the cost of some performance.

For the average user, leaving it enabled in the BIOS is the best approach.