Changing number of cores in msconfig affects computer speed?

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W00dmann

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Jun 21, 2014
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This may sound like a silly question, but please bear with me. I have a new USB mouse - my first bluetooth wireless mouse - and I'm having the dreaded "mouse pointer lagging when computer busy" issue. I'm using Windows 7 on a desktop computer, an older i7 i920 (16GB RAM). I've tried adjusting many settings with little effect. One thing I read about was that the computer may not be recognizing all my CPU cores correctly. So I went into Windows Task Manager => performance tab and counted 8 cores showing. 4 of them had squiggly green lines indicating they were busy "performing" and such, and the other 4 were largely squiggly-free, with only a few lines showing. Well ok I thought, at least it seems to be recognizing 4 "real" CPU cores and 4 "virtual" cores (is that due to hyperthreading?).

In any case, I went into Msconfig and went to the Boot tab => advanced options, put a tick in the "Number of processors" box, and changed the number of processors to "4". I wanted to see what would happen.

I rebooted the computer and now in Windows task manager, I see only 4 cores. Ok, got it - so forcing Msconfig to recognize "4" CPU cores was the wrong thing to do, right?

The only thing is, I can't seem to detect any noticeable degradation in performance. In fact, performance seems a tiny bit snappier (subjective bias?) and the mouse lag doesn't seem to be there anymore - at least, not for now.

So my question is: did I in fact hobble my PC's performance, or not?? I don't understand how "reducing" the number of visible cores in Windows 7 could have resulted in an unaffected PC performance. Very odd indeed.

Thanks for your help!
 
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Unless you were actually using all 8 cores, whether real or hyperthreading, changing the number of cores available to Windows is hardly going to change much.

Once you reduce your system to two or fewer, you'll start to see a more noticeable difference.

Really though, it's like having a car with a governor that allows you to hit 200 mph, then setting the governor to 100 mph, while driving 25 mph down a residential street and saying, I don't feel like I'm going any slower. That's because you're not. The maximum potential of your CPU has been reduced, but you're clearly not taxing it while at the Windows desktop.
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lucas7004

lucas7004

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Cores don't upgrade the speed so try to over clock the CPU slightly instead which should increase performance. But if it is still too slow, you might need to replace it or upgrade it and the motherboard.
 
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bigpinkdragon286

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Unless you were actually using all 8 cores, whether real or hyperthreading, changing the number of cores available to Windows is hardly going to change much.

Once you reduce your system to two or fewer, you'll start to see a more noticeable difference.

Really though, it's like having a car with a governor that allows you to hit 200 mph, then setting the governor to 100 mph, while driving 25 mph down a residential street and saying, I don't feel like I'm going any slower. That's because you're not. The maximum potential of your CPU has been reduced, but you're clearly not taxing it while at the Windows desktop.
 
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bigpinkdragon286

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A great explanation of core parking from here:

"Normally in a hyperthreaded CPU the on-core cache is shared between the two threads that the core supports.

The main gain for core parking is that when the system is not heavily multi-tasking the hyperthreaded cores can be parked, this allows the CPU to reallocate the entire cache on each core to 1 thread instead of 2.

What this should mean is that under low active thread counts the computer (such as you would find while playing a game) the actual performance for those threads is higher because they have a larger on-CPU cache.

Multithreaded applications tend to be large data processing applications so the hit from loosing cache is generally compensated by higher availability of processing power when the cores are unparked.

To an extent this is one of those 'best of both worlds' type things, you gain speed when the system is running just a few heavy threads and gain processing power in multi threaded applications.

What you loose by disabling core parking is the extra performance afforded by a single threaded application having a larger on-CPU cache."
 
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