i5 quad core showing only 2 cores

Holy Nick

Honorable
Jan 26, 2014
11
0
10,510
1.My BIOS all show 4 cores
2.Task Manager and Device Manager show 4 cores
3.But my cpu-z and performance information show only 2 cores.
Things that i did tried to solve but it won't work :
1. Unchecked the " number of processors " under msconfig/boot/advanced options
 
Solution

what pc do you have - laptop or desktop?
what cpu model name and number does cpu-z show? can you post a screenshot? check the no. of cores and no. of threads sections for details.
intel's mobile core i5 and at least 1 desktop core i5 cpu per gen have 2 real cores with hyperthreading to execute 4 threads. those dual cores show 4 cores in task manager.

 


I'm running a desktop.
Intel core i5 650
Cpu z show 2 cores 4 threads
e649.png
 


Thats it! 2 Cores and 4 threads. Your Cpu IS a dual core.
 
Solution


Actually, can you explain threads?
 


The core count is the physical number of cores on the CPU die itself, whereas the thread count is the number of individual application threads which can be executing simultaneously on the CPU itself. Without any additional or special hardware, this is always equal to the core count.

Some Intel CPUs have a feature called hyperthreading, which allows an operating system to see double the amount of logical cores per physical core. This allows the operating system to schedule and run double the amount of threads simultaneously, so in the case of the CPU I linked to above, there are four physical cores, but eight logical ones (so you can run eight threads simultaneously).

Each individual application running in the operating system is either single-threaded or multi-threaded (think of each thread as a "sub-application"). Single threaded applications require just one thread to run on the CPU, whereas multi-threaded applications have many sub-threads running simultaneously. Additional cores, or hyper-threading, allows more application threads to simultaneously run at once.

This allows multi-threaded (not single threaded) applications to run much faster, since more then one thread can run at once on the CPU.
 


Thanks man, u made my day!
 


Your welcome
 
Actually, the hyperthreading "cores" do present themselves to the OS as normal processors. That's why you can also call them "logical" cores. If you have dual core CPU with hyperthreading, then the OS sees four cores. That's the beauty of this technology. The OS sees many cores. It's is INSIDE the hardware of the cores that they happen to share some facilities. Hyper-threading does not make your multithreaded apps run much faster. The number I have heard is 10 to 30% faster for _heavily multithreaded_ applications or multiple processes. If your application is bottlenecked by a single massive thread, then hyperthreading does nothing for it (as well as having multiple real cores)
 


s0 does it mean my performance is equal to a quad core cpu?
 


Yeah.
 


Actually that depends. Depending on the application is when CPU benefits from Hyperthreading. Most PC games do not use HT, so the i5 will simply be a dual core. However, there are many applications for every day use and applications that require heavy graphic rendering that will benefit from HT.
 


Absolutely not. See my reply again. A CPU with hyperthreading, shares some execution units between the pairs of cores, and so the instruction streams from two different threads/logical cores will take turns to execute on the actual execution unit. This still has benefits over plain two core, but not as fast as real four core.
 


I am only judging it prior to the benchmarking results
 
BIOS update didn't solve it. CPU-Z still was displaying 2 cores 2 threads.

What did my day was:
bcdedit /set numproc 4

After reboot CPU-Z successfully reported 4 cores 4 threads.
http://www.majorshare.com/cpu-m-benchmark/ showed me an improvement from 11k to 19k points.