Not all CPU cores are recognized

Prkl

Honorable
Jan 21, 2014
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10,510
I have i5-4200U (Dual-core, 4 threads) but CPU-Z and Core temp only show that it has 1 core and 2 threads.

See image below for extra info
http://puu.sh/6t2OI/a3127abed7.jpg

How do I fix? I haven't seen option in BIOS which would let me change the number of CPU cores either.
I've updated to the latest BIOS; Still no option for changing the amount of cores.
And as you can see in the image; I've changed the value of cores in msconfig from 1 to 2, or am I missing something obvious, and both cores are working..?
Currently on W8.1 Pro

HOW TO FIX, Possible solutions TLDR version:
-Unpark your cores
-MAKE SURE YOU UNCHECK THE ''Number of processors'' box in Advanced boot after changing it.. lol. This was why my laptop was using only 1 core. I forgot to uncheck it after changing the value to 2.
 
Solution
I believe that particular i5 is set to deactivate its 2nd core (and the 2 threads) when it's not doing anything demanding, as the U processors are ultra low voltage processors designed to conserve as much power as possible

Prkl

Honorable
Jan 21, 2014
9
0
10,510


Ah, brilliant.
I'll launch couple more demanding programs and we'll see how it goes.
Thank you!
 

dgingeri

Distinguished
It'll park the core and eliminate power to it, but I believe it would still be reported. There is a BIOS setting in most machines that can turn off cores, though. Try looking there if the above approach doesn't work.
 

Prkl

Honorable
Jan 21, 2014
9
0
10,510


I will see.
By the way; is there any way to force the PC to use both cores constantly?

Edit: I used http://www.coderbag.com/Programming-C/Disable-CPU-Core-Parking-Utility to unpark both cores.
I don't know does it help really.. CPU-Z still shows only 1 core and 2 threads.