Hyperthreading question on i3

[QMarc]

Hi,

I recently bought a new i3-4170, and I realised that most of the time the 2nd virtual core (CPU4) was barely used during light to medium loads, sometimes staying even around 0%, but catches up with the other cores when under heavier loads (usually above 60%). It properly goes up to 100% during stress tests, and the Intel Processor diagnostic tool told me everything was ok apparently.

Is that a normal thing for hyperthreading or is my CPU faulty ? I couldn't find if it was a feature to save power in the BIOS either.

Edit : After some more testing, it looks like my CPU erratically uses the 4 cores as he pleases, whether it's during gaming or other tasks.

For example, in some games the first and 3rd cores would be around 70% when the other are at 0%, most of the time the 4th core will stay at 0 until the first three are "filled" at around 50-60%, it varies from task to task. I was comparing this to similar performance test videos on Youtube from other users, and all of them have usually their 4 cores almost evenly balanced depending on load (eg. 30%-ish on every core when at low usage, 70% everywhere at high usage). So I'm starting to think that my CPU is indeed faulty, or there is some kind of option somewhere regarding power save or hyperthreading that might cause this.

I'm also under Windows 7, and I also read somewhere that Windows 7's use of hyperthreading might cause this.

I'd really like to know since my hardware is still under warranty. I'm gonna ask my retailer during the week.

Thanks in advance,

mechmaster90

[QMarc · Accepted solution]

Hmm all right, thanks for the answer, so is that normal if when I run a specific game, my CPU works at 50%/20%/50%/0% on average (the first physical core+virtual core, and the 2nd physical+virtual cores, respectively), whereas people with the exact same specs (OS and GPU as well) run it at 30/30/30/30 average ?

Edit : So after some intensive googling, I found the answer, it's called "core parking", it's apparently a feature to save power, mostly for laptop users (which I also happened to have on my desktop for some reason) to use the first cores as a priority before using the last ones, and so with hyperthreading, it favors the usage of the 2 physical cores (actually labeled CPU1 and CPU3, or core0 and core2 in the task manager), and then the 2 virtual cores (CPU2 and 4, or core1 and 3), which explains my numbers.

After changing a few values in the registry (youtube it if you happen to have the issue too), all cores get "unparked" and now all of them work at an almost evenly rate during tasks. This also solves some FPS issues on some games which have poor management of core usage, especially hyperthreading, and should make your CPU benchmarks more consistent as well.